A Wikipedia Administrator is registered user at the online encyclopedia that has a number of "privileges" that allow them to do certain things regular users cannot. Wikipedia Admin are nominated and elected by other editors. They do not moderate the site, as is seen on message boards, as the site itself is maintained by the consensus of all involved or contributing to the discussion of a given subject. They have the ability to remove comments permanently, ban users and do a number of task associated with the encyclopedia when needed.
The Wikipedia Administrator was asked to scrub a comment on the talk that was uncivil and and went against the spirit of Wikipedia.