The manager of a Manassas roller rink accused in a complaint of racial bias testified yesterday that his wife threw away a mallet now being sought in the lawsuit as evidence of an alleged policy of intimidation of black patrons.

Gary L. Quintin, manager of Roll on America, acknowledged under questioning from U.S. District Judge Oren R. Lewis that the mallet had existed, but was disposed of "a month or two ago."

The complaint, filed July 2 on behalf of three Northern Virginia teen-agers, alleges the mallet was inscribed with "Gary's Little Nigger Beater," kept in Quintin's office at the rink and part of an alleged policy to discourage black and white teen-agers from skating together.

Lewis yesterday denied as "premature" a request by Alexandria lawyer Victor M. Glasberg, who represents the plaintiffs, for a court order that the mallet be preserved as "extremely significant evidence" in the case. Lewis said sworn statements by witnesses that the mallet existed--statements Glasberg told the judge he has--might be as significant as the mallet itself, if the dispute goes to trial.

Quintin denied in an interview shortly after the lawsuit was filed that he kept such a mallet. "No such thing," Quintin said. Quintin was not asked yesterday whether the mallet bore the alleged inscription, but acknowledged that the mallet he said was thrown away was the same item cited in the lawsuit.