How to insert avatar into user profile?

(See attached image)

The profile editor is not allowing the upload of avatar images. Under "Change Avatar Image", it has buttons for "SAVE" and "CANCEL", but there is no way to upload anything.

The Avatar feature has been disabled.

Is there a way to remove avatar?
I don't want any avatar but forum uses mine from Facebook I guess... And I can't change nor remove it.

Hm. I registered to Facebook with different mail but this forum still shows the same avatar!?
Anyway, how to remove it? That gravatar site is totally unclear - no way I can remove my avatar here and there?

UPDATE: Done - I really had account there (have no clue since when?!) - I logged in using one of my passwords (!) and remove picture. This is OK now.
Thanks!