According to the preface to the English Standard Version (ESV)...

... the Jewish people considered the personal name of God to be so holy that it should never be spoken aloud. Instead of reading the word YHWH, they would normally read the Hebrew word 'adonay ("Lord"), and the ancient translations into Greek, Syriac, and Aramaic also followed this practice. ... As is common among English translations today, the ESV usually renders the personal name of God (YHWH) with the word Lord (printed in small capitals). An exception to this is when the Hebrew word 'adonay appears together with YHWH, in which case the two words are rendered together as "the Lord [in lowercase] God [in small capitals]."*

See also YHWH. Catholic authorities simply copied a Jewish tradition and altered the original Word of God by replacing His Name with LORD, according to human tradition. But is it legitimate to change the Word of God?

Exodus 3:15 (TS2009)
And Elohim said further to Mosheh, "Thus you are to say to the children of Yisra'el, 'YHWH Elohim of your fathers, the Elohim of Abraham, the Elohim of Yitshaq, and the Elohim of Yaaqob, has sent me to you. This is My Name forever, and this is My remembrance to all generations.'

Exodus 20:7 (TS2009)
You do not bring the Name of YHWH your Elohim to naught, for YHWH does not leave the one unpunished who brings His Name to naught.

The Jews who deleted God's Name from the inspired Scriptures based their idea basically on Exodus 20:7. God inspired His Name to be written in the Old Testament more than 6800 times. Obviously God would not inspire His Name to be written if it were too holy to be used or pronounced by humans. By replacing God's Name in the inspired texts they obviously violate His Word. God Himself said that He did not give His Name to be forgotten. He said that mankind should not bring His Name to naught, which is exactly what they did by taking His Name out of His Word and replacing it with a title. Obviously no reason made up by people can possibly justify the replacement of His unique and Holy Name. Nevertheless, the Catholic authorities copied this practice. Countless Christians rant Our Father in heaven, hallowed be your name... but they don't even know God's Name because it was erased from His inspired Word. Extraordinary. They replaced it with the title 'LORD'...

In the photo a limestone relief from Palmyra (Syria) showing the moon god Aglibol, the supreme god Baalshamin, and the sun god Malakbel (from left to right). First half of the first century CE. Exhibited in the Louvre Museum, Paris. The moon god is also known as Allah from Islam. The sun god points to sun worship. Baalshamin is inbetween as the supreme god. It is also a reference to the pagan trinity belief.

Jeremiah 23:26-27 (TS2009)
Till when shall it be in the heart of the prophets? — the prophets of falsehood and prophets of the deceit of their own heart, who try to make My people forget My Name by their dreams which everyone relates to his neighbour, as their fathers forgot My Name for Ba'al.

Lord is an appellation for a person or deity who has authority, control, or power over others acting like a master, a chief, or a ruler. ... Lord is used as a title of deference for various gods or deities. The earliest recorded use of Lord in the English language in a religious context was by English Bible translators such as Bede. It was widely used in the King James Bible translated in the 17th century. ... Baal ("Lord") was used by the Canaanites both as a generic term of address to various local deities and as the spoken name for the storm god Baal Haddu once the form "Hadad" became too sacred for any but his high priest to utter.*

The word 'lord' can mean any god. Christianity took out the unique Name of God and replaced it with a word which means 'any god'. This practice was copied from the pagan Canaanites and their polytheistic pantheon. To wipe out God's inspired Name from His own Word and replace it with 'LORD' is simply against God.

Biblical narrative incorporates tales of Baal worship into the traditions of the wilderness wandering, thus tracing Baal worship to the earliest period of Israel's existence. At Shittim they attached themselves to Baal-Peor, ate sacrifices for the dead, and indulged in sacred sexual orgies (Num. 25:1–11; Ps. 106:28).*

In the book of Kings, we see that the Ten Lost Tribes began to worship a sun god named Baal, who is mentioned over 80 times in the Bible. They did not repent of it, and as punishment, eventually, they were taken into captivity around 700 b.c. and they never returned to their former identity or to the true God.*

1 Kings 18:21 (TS2009)
And Ěliyahu came to all the people, and said, “How long would you keep hopping between two opinions? If YHWH is Elohim, follow Him; and if Ba‛al, follow him.” But the people answered him not a word.

According to Strong's Concordance the word baal means 'owner' or 'lord'. It is also a link to sun worship. Catholicism is drenched in it. Would Almighty God YHWH appreciate it if we call Him by a word which means 'any god'? Would He appreciate it if we replace His unique Name with something inferior which opens doors to pagan ideas? Would He appreciate it if people corrupt His perfect Word and teach this to millions of people? If this practice doesn't come from God, then from where does it come?

Baal was a title and honorific meaning "owner", "lord" in the Northwest Semitic languages spoken in the Levant during antiquity. ... The Hebrew Bible includes use of the term in reference to various Levantine deities, often with application towards Hadad, who was decried as a false god. That use was taken over into Christianity and Islam, sometimes under the form Beelzebub in demonology.*

From Hebrew ... (Ba'al Zevuv) meaning "lord of flies" ... intended as a mocking alteration of ... (Ba'al Zevul) "Ba'al the exalted", one of the Canaanite names for their god BA'AL.*

In Islam the same thing happened. They copied the Catholic idea of LORD and used the generic title Allah, which simply means [any] God, and their false prophet Muhammed started dictating his own unscriptural ideology. So we know now that the word baal refers to many gods. But according to the Scriptures there is only one Almighty God. And God has an adversary who wants to be like God. His name is Satan. In the Gospels there is mention of a certain Be'elzebul who is called the ruler of the demons. And that is Satan. According to the catechism of the Catholic Church: The goal of a virtuous life is to become like God* and "to become like God" was exactly the trick used by Satan to deceive Eve in the Garden of Eden. The Catholic Church is one of the tools used by Satan to deceive mankind.