Jacob Mellis has left Chelsea by mutual consent after he admitted setting off a smoke grenade at their training ground.
The Blues confirmed on Tuesday they and 21-year-old Mellis, who has played for the first team, had "parted company" following a "full and thorough" investigation into the incident which took place on March 2.
Team-mate Billy Clifford escaped with a fine after admitting he brought the grenade - understood to be from a paintball expedition - into Chelsea's Cobham training headquarters.
According to reports, the smoke grenade was set off in the reserve-team dressing room and trained fire marshals had to be brought in.
Players, officials and other staff from Chelsea's reserve, youth and academy teams ran from the building with hands covering their faces because of the thick smoke.
Owner Roman Abramovich was reportedly briefed about the incident, which occurred shortly before training at 10.30am and set off fire alarms and triggered a full evacuation procedure.
Mellis joined the Blues from Sheffield United five years ago and made his debut in the UEFA Champions League win against Zilina in November 2010.
Clifford, 19, is a regular in Chelsea's reserves and signed a new four-year deal last summer.