The fact that Evernote doesn't allow for "right-click" on the actual Tag when unnested / unfolded in the left side-pane menu is ridiculous. Intuitively, you should able to do both:
Edit / Rename the Evernote Tag by right-clicking the Tag name when unfolded
Edit / Rename the Evernote Tag by going to the "Tag Area" and right-clicking to view options.
Evernote makes it increasingly difficult to find simple, editing tools and configuration preferences. I've got a list of about 20 things that Evernote could do to improve, but they're so far behind after the 2017 company crash that I worry they'll never catch up.