"I will not be returning to @RoseanneOnABC," Sykes tweeted. The comedian was a head writer for "Roseanne," which returned for a tenth season in March.
Barr was met with criticism after she likened Jarrett, who is African-American, to the Muslim Brotherhood, a conservative organization in Egypt, and the film "Planet of the Apes."
"Muslim brotherhood & planet of the apes had a baby=vj," Barr wrote in response to a comment about Jarrett on Twitter.
Barr then apologized for the statement and said she was leaving Twitter. ABC has yet to comment on the incident.
"I apologize. I am now leaving Twitter," she said.
"I apologize to Valerie Jarrett and to all Americans. I am truly sorry for making a bad joke about her politics and her looks. I should have known better. Forgive me-my joke was in bad taste," Barr continued.
"Roseanne" was renewed for an 11th season in March.
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