TERMINATION OF MEMBERSHIP.
Tex. GOV'T Code § 812.005.
in effect(a) A person's membership in the retirement system is terminated by:
(1) death of the person;
(2) retirement based on service credited in all classes of membership in which the person has service credit; or
(3) withdrawal of all of the person's accumulated contributions.
(b) A person terminates membership in one class of membership by:
(1) retirement based on service credited in the class; or
(2) withdrawal of the person's accumulated contributions for service credited in the class.
(c) A person may terminate membership in one class and retain membership in the other.