Aborting a game can be done only at the very beginning of the game by either:
A. Not doing anything when it's your turn until the website decides you're not going to play
B. Closing the tab
Please keep two things in mind, however:
1. If you do this too frequently, eventually your aborted games will be counted as resignations instead, which do count as losses and will cause you to lose Elo.
2. What I said only applies to normal timed games, as far as I'm concerned. I don't know if it's any different for daily games.
Its with a friend, and he had already started another game.