This command removes your target from the faction with the specified ID.
removefromfaction [faction id]
|Faction ID||The ID of the faction to remove your target from.|
The ID of the Crime Faction Winterhold is 0002816F. The above command would remove your target from this faction.
This console command is similar to the first example. As the command is prefixed with 'player.', your character will be removed from the Winterhold faction, rather than your target.