Coach Jim Mora announced Lucien's departure on Tuesday after the opening workout of spring practice.
The redshirt senior from Encino, California, has one more year of college eligibility.
''He has decided to go a different direction,'' Mora said. ''I thought I knew what that direction was, but as of this morning I don't know. But he will not be a part of this program anymore.''
Lucien caught 58 passes for 752 yards and four touchdowns in three seasons at UCLA, making eight career starts.
Lucien ranked third on the team with 29 receptions last season, failing to take a more prominent role in the offense despite ample opportunity. He caught a touchdown pass in the Alamo Bowl win over Kansas State.
''I wish he was out here with us running and catching, but I wish him the best,'' receiver Jordan Payton said.