As long as the Roster Deadline has not passed, a Captain can perform their own roster maintenance - just have them click the "x" next to the Player who they want off their team.
If a player has paid, and then is removed by their Captain, they will not be refunded - all refunds must come through the Back End Admin. It is important to complete all back-end refunds for the player before the captain removes the player from the team. This eliminates headaches for all parties involved.
If the roster deadline has passed and captains want a player removed from their team, they must contact your office and request for an admin to remove the player manually.