Exodus 23:21
Be attentive to him and obey his voice; do not be rebellious toward him, for he will not pardon your rebellion, since My name is in him.
This verse is about the angel of Jehovah, who trinitarians claim is the preincarnate Jesus.
God who is identified as one person who is also the speaker of this verse said: "My name is in him". Whose name? The angel's own name?
There are two different persons identified here: God who is the one in red and talking in the first person and the angel who is the one in blue and to whom God referred in the third person, and the name belongs only to the one who is identified in red (God), not to the angel.
God did not say that His name also belonged to the angel (the trinity doctrine claims that the name Jehovah belongs to the angel the same way it belongs to the Father because it claims that Jehovah is not a single person but three, this verse debunks that claim).
John 5:43
I have come in My Father’s name, and you do not receive Me; if another comes in his own name, you will receive him.
Jesus who is the speaker of this verse said that the name in which he came is not his own name, it is the name of only the Father.
Jesus contrasts himself who did not come in his own name with the other one who comes in his own name to emphasize that the name Jehovah in which he came is not his own name.
Revelation 3:21
The one who overcomes, I will grant to him to sit with Me on My throne, as I also overcame and sat with My Father on His throne.
Jesus is also the speaker of this verse. On whose throne did Jesus say that he sat? On the triune being's throne? Did Jesus say "our throne"? No. This is one person's throne, the Father's throne, His throne.
Revelation 1:4-5
John to the seven churches that are in Asia: Grace to you and peace from Him who is, and who was, and who is to come, and from the seven spirits who are before His throne, and from Jesus Christ, the faithful witness, the firstborn of the dead, and the ruler of the kings of the earth...
Before whose throne are the seven spirits? His throne. And to whom does "His" refer? To the triune being? No, Jesus is clearly mentioned in this passage but excluded from being the owner of this throne.
The "His" clearly refers to only one person: the Father, who is identified here by the title: "who is, and who was, and who is to come".
Revelation 1:8
“I am the Alpha and the Omega,” says the Lord God, “who is and who was and who is to come, the Almighty.”
How many persons is the Lord God in this verse? Clearly only one person: the Father "who is and who was and who is to come". Only He is the Almighty, this is not a triune Almighty nor a triune Jehovah, only one person is the Almighty and Jehovah.