Request to remove an author after publication

Clarify the reason for the change of authorship (There are three possibilities)

First:

The author(s) provide acceptable reasons for the change
Check that all authors agree to the change (including the excluded author)
Post the fix

Second:

The author(s) allege fraud or misconduct
See guidance on fabricated data

Third:

The authors disagree in their interpretation of the data

So:

Suggest the author(s) state their point(s) in a letter, clarify that you will give the other authors the opportunity to respond, and publish both letters if appropriate (e.g. ., if they are of appropriate length and without defamation). For it:

The author(s) write a letter

- Contact the other authors and explain what is happening. But:

If the other authors send a response, both letters will be published
The other authors do not wish to respond, so the letter with the minority point of view will be published

The author(s) do not agree to write the letter (or write an unpublishable letter) so if the author insists on name removal and the other authors agree, then you should consider publishing a correction