Manager John Felske announced that Carlton would not be offered a contract.
Phillie pitching coach Claude Osteen, a friend and booster of Carlton, was asked if he'd sign him if he were a pitching coach for another team.
"Not unless I was desperate," Osteen said. "I would take a young pitcher who can overcome a few mistakes. Lefty can't do that anymore."
Carlton, 42, has a 323-229 record and is the game's second-leading strikeout pitcher. He is the only pitcher to win the Cy Young four times.
Carlton was dropped by the Phillies last June and later signed with the San Francisco Giants. When the Giants dropped him, he moved to the Chicago White Sox, who released him at the end of the season.
This spring, unable to get a chance with any other club, Carlton asked Phillie President Bill Giles and the Phillies to give him another chance. Giles agreed to let him work as an unsigned, nonroster player.
Carlton pitched 14 innings in exhibition games. He allowed 13 hits, 11 runs (7 earned), walked 6 and struck out 3.