Bug overview description.
When editing the artist page for blpanda, I tried to remove the twitter link from the notes section because I had moved it to the links section, but when I click save it doesn't remove the link from the note.

What part(s) of the site page(s) are affected?
Artist page.

What is the expected behavior?
Deleting the entry should leave the notes section blank.

What actual behavior is given instead?
The edit doesn't save. Opening it up to edit again presents the original section contents.

Can you reproduce the bug every time? yes

What steps did you take to replicate this bug?
Click "Edit", and delete the text, then click "Save".

Errors or other messages returned (if any).
none

I believe this is because it edits the wiki page, and wiki pages cannot be blank. If they are blank it assumes no update.

If you need to blank it, just set it to ".", or you can report the wiki page requesting for it to be deleted. https://e621.net/wiki/show/blpanda

Hmm. I was trying to edit this page (where you go when clicking the "?" in the tag list on the posting index).

I popped it using the "." you suggested, but I've edited other notes sections before without issues, which is why I brought it up here.

(Though, now that I think of it I don't think any of the edits were removing all the content in the entry field. Hrm.)