A conservative commentator in the St. Louis area has lost his television and radio shows after saying on Twitter that he was preparing to use a “hot poker” to assault a survivor of the Parkland, Fla., school shooting.

In the crude tweet, Jamie Allman, the commentator, said that he was “hanging out getting ready” to assault David Hogg, one of the outspoken survivors of the shooting in which 17 people were killed. “Busy working; preparing,” Mr. Allman added. (Mr. Allman has since made his Twitter account private.)

Mr. Allman had shows on KDNL, an ABC-affiliated television station owned by the Sinclair Broadcast Group, and KFTK-FM, a radio station owned by Entercom Communications.

“We have accepted Mr. Allman’s resignation and his show has been canceled,” Ronn Torossian, an outside spokesman for Sinclair, said by email. A spokeswoman for Entercom said that the broadcaster and Mr. Allman had parted ways. He had been with the radio station for about 12 years, she said.