I was playing a chess game with a highly rated person in a tournament, and his dad was watching over the game. Obviously, it didn't affect the game, but I would have felt better if he was not watching over the game. Should I just deal with him being there? How do I politely ask a spectator to not watch the game I am playing?
Inform the arbiter that it's affecting you, that's more or less all you can do.
Other players in the playing hall and spectators if they're allowed in are allowed to watch your game. But not to interfere with you or distract you.
So if the spectator goes over the line, the arbiter can tell him to take more distance, or leave the playing area. But by itself the fact that he is watching isn't enough, I'd say.