In releasing Burleson ($5.5 million) and Delmas ($6 million), the club saved $11.5 million and are now under the projected cap of $126 million by more than $5 million, according to the team website.
Both players have been hampered in recent seasons by injuries.
Burleson, 32, was a capable sidekick for top receiver Calvin Johnson in his first two seasons in Detroit, averaging 64 catches, but had been hampered by injuries the last two seasons missing 17 games.
He recorded 12 touchdowns in four seasons with the Lions after previous stints with the Vikings and Seahawks.
The 26-year-old Delmas, a 2009 second-round pick by the Lions, has battled through knee issues the last three years. He missed five games in 2011, six in 2012, and, despite playing in all 16 games in 2013, missed a lot of practice time.
The Lions are coming off a disappointing season in which they lost six of their final seven games for an overall 7-9 record and missed the playoffs, a performance that cost head coach Jim Schwartz his job.
Jim Caldwell has taken over the reins in his second run as a head coach after holding the top job with the Indianapolis Colts from 2009 until 2011.
(Reporting By Andrew Both in Cary, North Carolina; Editing by Larry Fine)