49ers linebacker De’Vondre Campbell was active in Thursday night’s game against the Rams but never took the field. San Francisco coach Kyle Shanahan said after the game that it was because Campbell left the team and refused to play.

Campbell was seen leaving the 49ers sideline during the game, and when asked about it, Shanahan said that it was Campbell’s decision.

“He said he didn’t want to play today,” Shanahan said. “He did when I asked him why he didn’t want to go in. That was in the third quarter.”

When asked if this had ever happened to him before, Shanahan replied, “No.”

Campbell played all season for the 49ers but was not in the starting lineup Thursday night as linebacker Dre Greenlaw returned from his Achilles tendon injury. Shanahan said the plan was for Campbell to play in the game as Greenlaw’s replacement, but when Greenlaw went out, Campbell quit.

“He was going in when Dre came out,” Shanahan said.

Shanahan didn’t answer definitively when asked if the 49ers would cut Campbell, but he seemed to be leaning in that direction.

“We’ll figure something out, but I don’t know right now,” Shanahan said. “When someone says that, you move on. You don’t deal with it anymore. . . . If someone doesn’t want to play football, it’s easy. I think our team and I know how we feel about it, so I don’t think we need to talk about him anymore.”