''Free at last free at last,'' Phillips wrote in an Instagram post that was later deleted. ''Good luck to my brothers on the team. I'll miss ya'll, but I couldn't be happier to be out of there. ... Sometimes you got to put your future in your own hands and live with it.''
Phillips and the rest of Miami's front four were dominated in Sunday's 38-7 loss to the Patriots, who rushed for 175 yards.
Phillips said his flare-up during the game didn't play a role in his release.
"Just here to squash this sideline outburst stuff.... this move had nothing to do with that,'' he tweeted.
The Dolphins (3-1) had the day off and didn't discuss the reason for the move. On Monday, coach Adam Gase defended defensive line coach Kris Kocurek's substitution pattern.
The Dolphins also placed center Daniel Kilgore on injured reserve with a triceps injury. They signed center Wesley Johnson and promoted defensive end Cameron Malveaux to the active roster from the practice squad.
Johnson, who becomes Miami's backup center behind Travis Swanson, made 24 starts for the New York Jets in 2015-17 and was with the Detroit Lions during training camp this year. Malveaux played in four games as a rookie last year.
Phillips was a second-round draft pick in 2015 who has 26 starts and developed a reputation as an inconsistent underachiever. He came off the bench this season as part of the defensive line rotation, and had one sack and five tackles.
Gase has spoken often about his desire to improve the team's culture following a 6-10 season in 2017.
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