Reece did not respond to text messages Monday but had been looking forward to returning to the Raiders at the end of training camp.
"I'm gonna make the best of it," Reece texted at the end of the preseason. "[I] will be waiting on the air strip when my guys land from Tennessee on Sept. 25.
"I'm gonna be a nightmare for Baltimore!"
Instead, the Raiders, who have been carrying 52 players on their 53-man roster since the start of the regular season, parted ways with him on Monday, six days before Oakland plays at the Baltimore Ravens.
Reece was suspended before the final game last season for violating the NFL's policy on performance-enhancing substances.
"I want to thank Marcel as a player and as a person for all that he has given to the Oakland Raiders," Raiders general manager Reggie McKenzie said in a statement. "What he has meant to the organization and to me over the past few years is hard to put into words, but his actions, both on and off the field, speak louder than any words can. This was a tough decision. Not enough can be said about Marcel's commitment to his teammates and his pride in the Raiders, and we wish him and his family nothing but the best."
Reece, a close friend of owner Mark Davis', was also the longest-tenured position player on Oakland's roster, having joined the Raiders as an undrafted free agent in 2008. Only Sebastian Janikowski, the team's first-round pick in 2000, has been in Oakland longer.
"Today is a sad day for the Raider family and entire Raider Nation," Davis said in a statement. "My father once said that I would have a tough time running this organization because I was too close to the players, and that rings true today. Marcel Reece has been a pillar of the organization for nine years and was the glue that held us together during a tough transition after my father's passing. He helped put us on the upward path we are on today and his leadership will be sorely missed. The motto, 'Once a Raider, Always a Raider,' has never been more appropriate. When Marcel finishes his playing career, there will always be a spot for him within the Raider organization."
A converted college receiver at Washington, Reece was second-team All-Pro in 2013 and had 15 career touchdowns in 92 games with 67 starts for the Raiders. He had 205 catches for 2,015 yards and 12 scores and carried the ball 183 times for 844 yards and three touchdowns.
Though Reece served the league suspension, he maintained his innocence. He said a legal "natural plant root extract by the name of Umcka" he ingested converted into the banned substance "metylhexanamine."
He was allowed, though, to be around the team during the offseason program.
Raiders coach Jack Del Rio said in his weekly media conference on Monday that the he did not "know that the suspension played a big part in the decision."
Depth in Oakland's offensive backfield, with rookies Jalen Richard and DeAndre Washington playing well, along with fullback Jamize Olawale and starting running back Latavius Murray, played more of a part.
"We feel like it's a good group," Del Rio said, "and we don't want to disrupt it."