Abandoned Game

If they abandon the game, they will get flagged by the Fair Play Policy. After doing that enough, they will mainly get paired with other people that do the same thing.

https://support.chess.com/customer/en/portal/articles/1444922-fair-play-policy
You just have to wait until the disconnect time is met, which should be 3 minutes. Or if they just stay logged in, you have to wait. There used to be a max move timer but that was removed at one point.