Are clones allowed to retire?
The cloned Troopers were born(cloned/created) to serve in the military. Were they ever released from service to become civilians?
There are several comments throughout the article on clone troopers in the Wookiepedia. They don't explicitly say they were never released, but the intent was that they were trained to be completely loyal (some of that was genetic conditioning, too), and bred only for combat. Some quotations from that article:
"Bred for the sole purpose of combat"
"They were bred for no other purpose than combat"
Essentially that's all. They were nothing more than slaves. They were bred for the Republic (or the soon-to-be Empire) and with no other purpose in their lives but to fight and die as soldiers.
They were less than individuals. One example of how much their lives mattered is a reference to "a company of clones that possessed less than 20/20 vision. They mysteriously disappeared in the late hours of the night and were never seen again."
Remember, while they were supposedly for the Republic, Palpatine's intent, from the start, was to take over and to have his own standing army of stormtroopers.