Chris -

Actually, upon termination of employment you have options...

(1) Leave the balance in the 403b account (and continue to manage it)

(2) Transfer it to another 403b or 403b(7) account

(3) Direct rollover to an IRA

(4) Total or partial withdrawal (and pay tax + penalty for premature withdrawal before age 59½)

You are not required to take installment payments (in the classic "annuity" mode, though it is an option).

Best wishes, PP