Administrators (also known assysops oradmins) onMediaWiki.org are users with the technical capability to protect and delete pages, block users, and edit protected pages, among other things.
To become an admin, ask atProject:Requests. Information on the promotion process can be found there.
Lists ofcurrent admins, andcurrent bureaucrats are available. To request a deletion, seeProject:Deletion.
Stewards andglobal sysops should feel free to deal with vandalism and similarly routine and uncontroversial things, if necessary (Note: These are global groups defined by theCentralAuth extension and don't appear atSpecial:ListUsers, but atSpecial:GlobalUsers).
