Board Thread:Support Requests - Community Management/@comment-25523075-20150607080852/@comment--20150609054757

If a user is adding spam categories that are not needed, you can leave a message on their wall, explaining you do not need those categories. And if needed, you can block them. If you are not an admin, you can report them to the local admins, or at the VSTF Wiki if no active admins are present.

If you are an admin on the Wii Sports Wiki, you can WHAM their profile, and it will undo all their edits.

I'm assuming it's this user? Their edits don't look like vandalism, so the VSTF probably can't help you there, so I would recommend contacting the local admins over the matter.