Board Thread:Support Requests - Community Management/@comment-45829731-20200616095324/@comment-44498734-20200616095846

Check Help:Blocking. basically go to Special:Block on your wiki, enter the username of the person you want to block, enter a time for the block and a reason, check if you need to change any of the special options and hit block this user at the left bottom of the screen.

Cheers!