Do you mean remove a tag from a highlight without deleting the highlight?
Or do you mean remove a tag from the list of possible tags which pops up when you choose to tag a new highlight?
Or do you mean remove a tag from the list which appears when you go to Notes > Tags?
(If either of the last two, please confirm that there are no highlights tagged with the tag you want to remove, and that you've power-cycled the device and tried after that.)
Edited 1 time, last by aebrown on . Reason: Remove duplicate content
Since there's been no reply here, but another post asked the same question, I'll crosslink the two so the answer is in both places... The other thread is:
[Moderator note from aebrown: I removed the duplicate content, since it is in the linked response. The link is very helpful; thanks for posting it. But please don't post duplicate content (that is prohibited by the Code of Conduct).]