According to the USBC rules, as long as the members follow the proper procedures for withdrawing. Rule 114 – Withdrawals/Resignations
They are entitled to the prize money.
You only forfeit prize money if you improperly quit the league.
Rule 114 – Withdrawals/Resignations
114a. Procedure for Withdrawing
Members of a league may withdraw from a league during a season.
1. If a team or individual must withdraw, the following procedure is to be followed:
a. Two weeks notice must be given along with sufficient cause for resigning.
1) A team shall give notice to the league secretary.
2) A member resigning from a team shall give notice to the captain and the
league secretary.
b. The resigning member(s) must pay league fees for two weeks if the bowler is not
replaced within that period.
2. If proper notice and sufficient cause is not given, all franchise, prize and any other money for which
the team or individual may have been eligible will be forfeited, unless the league board determines
otherwise. In addition, the member(s) shall be subject to suspension of USBC membership.