The CY2XF33 is a One Time Programmable (OTP) device and cannot be re-programmed after being programmed once.
Part numbers beginning with CY2XF33FLX are field programmable devices. They are unprogrammed when shipped. The user may program them once, using a programmer such as the CY3675 CyClockMaker.
Part numbers beginning with CY2XF33LX are factory programmed devices. They are programmed by Cypress prior to shipping, and cannot be reprogrammed afterwards.