"Tough game. Tough situation. No excuses. (Thank) you to the Bills organization!" Leinart wrote Friday, before deleting the tweet.
Leinart, 30, joined the Bills on Sunday as an injury replacement. The former first-round pick struggled in his only preseason game with the Bills, completing 3-of-10 passes for 11 yards and two interceptions Thursday night against Detroit.
The move was the latest setback for Leinart, the 2004 Heisman Trophy winner. Leinart has been unable to establish himself in the NFL following a standout college career at Southern California. He has had stints with four teams over the past eight years.
Information from The Associated Press was used in this report.