Board Thread:Support Requests - Designing Your Wikia/@comment-25301601-20140715193100/@comment-26975268-20140715224201

I know for sure this is not a feature accessibly by regular users, including admins. I have, however, seen that on w:c:disney the badge borders are customised. I'd say this was done by a member of the Wikia Staff on request.

I would recommend sending a Special:Contact/general to get a member of the staff to review all the info and tell you all you need to know.

Out of curiosity, why don't you want the border?