I presume you're trying to delete these games through MM.
You might have accidentally switched on a function in mm that precludes you from deleting anything. Go though the menu's and look for anything that reads like that or 'parental controls' etc.
Else try fixing permissions before you try to delete - you should do this to avoid an issue that used to happen with MM where the game appears to be deleted but the space is not recovered.
"We all agree your theory is crazy, but is it crazy enough?" - Neils Bohr