Patrick Hampton, who has served as vice president of Hamilton Flourishing since October 2018, said he is parting ways with the conservative group.
Mr. Hampton, who is unusual in being a black who is an outspoken conservative, said he would issue a statement after his last day on the job - Feb. 5.
He said the two sides "are in litigation."
Doug Daugherty, who heads Hamilton Flourishing, said a "negotiated severance" had been worked out with Mr. Hampton.
Mr. Hampton, who has a divinity/ministry degree from Covington Theological Seminary, earlier was business development coordinator at Chattanooga Goodwill Industries.
Meanwhile, Mr. Hampton said in a Facebook post that he is "currently being targeted by national leftist groups that are reporting me for leading a $tOp The $teal rallies in Nashville."
He said, "Our rallies were always peaceful and organized. We never called for violence or insurrection. Our speakers were well spoken and peaceful. Please stop the lies."
Mr. Hampton said he is currently having to secure a lawyer "due to all the issues stemming from leftist groups trying to cancel and attack me for my support of President Trump, law enforcement and conservative values. I will not back down.
"I was not at the Capitol in DC. I was not even in Washington, D.C. I did not support any violence. It is sad that people would use Photoshop, lie and use conjecture to destroy my reputation.
"All my personal pages have been banned by Facebook. This is my public page and they are sending warnings to ban this one. However, I will fight back. That's all I can say right now."
He said, "If you are a lawyer or just a follower that would like to help, please contact me."
Mr. Hampton also listed a link for "if you would like to donate to help in my defense."