"Mark Russell," UPI White House Correspondent Helen Thomas said several years ago, "plays the piano like Truman and the yo-yo like Nixon. He's been around a little longer than Nixon, but they do have one thing in common. Despite popular demand, they won't quit."

Yesterday, Russell quit. After 16 years at the Shoreham hotel, he walked away from the whole caboodle.

"He was out of town so much for one-righters and television," says Shoreham managing director Richard Abati, "and the lounge was dark and we were getting complaints from the hotel guests. So I approached him about going to weeken ds only, so we could have someone else in there, and I guess he didn't like it," I got a letter from him today.

"It's very sad. Mark has been very important to the Shoreham and very important to the Marquee Lounge. But we can understand his position."

Russell's manager confirmed that he had quit, but refused to comment further.

Russell himself was flying to Lansing, Mich., last night, and couldn't be reached for any bon mots.

So unless the dispute is settled, there will be no more feisty Russell one-liners at the crowded Marquee Lounge: "Jimmy Carter . . . I worry about a man whose teeth look like Chiclets"; "Gerald Ford reminds me of the guy who answers the meat buzzer at the A&P." And no more crowds sprinkled with the likes of Henry Kissinger. Ted Kennedy, David Brinkley, Bob Hope and Elizabeth Ray showing up to laugh at political humor after work hours.