Thread:Merrystar/@comment-6429245-20181015191141/@comment-11001-20181019051501

If there are other current contributors on the wiki you can create a discussion about demoting him; if you are all in agreement, send a message to Special:Contact with a link to the conversation.

However there is not a great deal that can be done otherwise; my best advice in that case is either to accept what you can and cannot change on the wiki, create a wiki of your own for the same topic, or find another wiki where your ideas and contributions will be better appreciated.