Remove an athlete from the agent's client list
Ends the representation (ENG-1465). The agent is detached from the athlete’s message threads, any social-link URL still outstanding for this pair stops working, and the athlete’s payout bypass is recalculated: sources scoped to this representation, including this agent’s approved agency W-9, stop counting. Historical payout records are untouched. Both the agent and the athlete are notified. Idempotent from the caller’s point of view: an athlete the agent does not represent is refused with ATHLETE_NOT_LINKED rather than silently succeeding.
DELETE
Remove an athlete from the agent's client list