Someone tagged this question as undergrad-education. Another user edited the question, deleted that tag, and added undergraduate-education. I approved the edit after seeing that undergrad-education has no user guidance and no other questions with this tag.
It would seem to me that this tag should be deleted. There is no value in having it be a synonym. How do I recommend that or can I do it myself?
A tag that is not used anywhere is automatically deleted after about a day.
Thus, the way to get rid of a tag used only very rarely so far is just to remove it everywhere as was done here.
In other cases, you can flag the post for moderator attention or raise the issue on meta.
Generally, actual deletions of tags need to go through SE not even moderators can do this. However, in case it is a duplicate tag, or subsumed by some other tag, moderators can "merge" the tag into the other tag, which amounts to a deletion of the tag.
