This command removes you from all factions. This will also remove you from the 'Player' faction. To re-add yourself to the 'Player' faction, use the command
player.AddToFaction 0001b2a4 1. Remember to also re-add the DLC player factions:
xx00B42E for Honest Hearts,
xx016154 for Old World Blues, and
xx003E41 for Lonesome Road.