Whitehead was getting clowned on social media for his lack of tackling and the overall terribleness of the Browns, when he lashed back on Twitter,

"Imma kill you bitch ... that's on blood," he told one guy.

"Don't get shot at lil bitch ... can you whoop my ass .. .f*ck football .. let me know when you need the address," he told another.

When one fan asked for Whitehead's address, the NFL player gave out the address to the Cleveland Browns facility in Ohio.

Twitter immediately suspended Whitehead's account over the threat -- in fact, it was suspended before he even left the locker room.

And, yeah ... as you could imagine, the Browns were PISSED too -- issuing a statement condemning Jermaine's actions.

"Jermaine Whitehead's social media posts following today's game were totally unacceptable and highly inappropriate," a Browns spokesperson said. "We immediately spoke with Jermaine upon learning of these comments. The Browns in no way condone that type of language or behavior. This matter will be further addressed internally."

Whitehead apologized ... but it was too late to save his job.

"I do apologize for my performance, but having a broke hand and a strong fear of letting my team down is my downfall," Whitehead said.

"Whatever happens happens. Ain trippin. They probably gone still talk crazy but this me getting smoke off my chest. I don't need one like.. this from me to me! Keep ya head up homie, can't nobody f*ck with you. I dare em to try."