publications - How to remove a co-author from an article published on arXiv?

I have published an article on arXiv. I associated person X as co-author whereas he didn't contribute at any step of the paper. Note that he is not registered as owner of the article on arXiv and I didn't give him the password to access as author.

When I wanted to submit the paper to a journal, X began to do some harassment. After that, I decided to remove his name from the article on arXiv.

Questions: How can I remove a co-author from an article published on arXiv? Can he claim that he is the co-author on arXiv or for a journal submission?

Answer

Yes, technically one can modify the authors of an arXiv article. See the replace instructions on arXiv. See also this answer on Quora. But, as far as I understand these instructions, the previous version with the initial co-authors will remain on the server.

Note that it was no good scientific practice to initially associate a co-author to the paper that didn't contribute to it. Regaring the claiming of the authorship by X after removing his name from the paper, I have no answer.