H. Lee Boatwright III was ousted yesterday as president of Suburban Trust Company, the largest bank, in Washington's Maryland suburbs.

President of Suburban Trust since April, 1977, Boatwright reportedly resigned after disputes with the bank's board of directors over management of the $1.3 billion financial instiution.

A new president will be named next month, said Robert Tardio, chairman and chief executive of both Suburban Turst and its parent holding company Suburban Bancorporation.

Surburban bankers speculated yesterday that the leading candidate for the job is G J (Bud) Manderfield, president of First American Bank of Maryland, an affiliate of Financial General Bankshares Inc.

Manderfield could not be reached for comment yesterday, nor could Boatwright.

Tardo refused to discuss the reasons for Boatwright's resignation, saying the bank is "standing on the (press) release" announcing the departure. The statement offered no explanation for the resignation.

"I don't want to be in a position to lend any credability to anything that's being said," commented Tardio. "Mr. Boatwright is hoping to stay in the financial industry. Comments should come from him."

Tardio, however, denied the resignation reflected differences between the two top executives at Suburban Trust. "There's nothing between Lee and me," he said.

Suburban's executive office will be reorganized when a new president is named, Tardio added. Tardio currently is chairman of the board, president and chief executive officer of Suburban Bancorporation and chairman and chief executive of Suburban Trust. As president of the bank, Boatwright was not president of the holding company and was not a member of the board.

Tardio suggested the new structure organization will be more like that of other local banking companies, which have one person as chairman of the lead bank and the holding company, and another as president of both organizations.

Sources familiar with the turmoil at Suburban Trust said relations between Boatwright and the board were the key factor in his ouster.

The board became used to dealing with a strong manager during the many years that J. Robert Sherwood served as chairman, one source explained. mSherwood, 75, retired as chairman in 1972, but remains on the board.

In contrast to Sherwood's autocratic style, Boatwright reportedly delegated much responsibility to Suburban's vice presidents, something neither the board nor the other executives were used to.

The ouster of Boatwright as president apparently had been in the works for some time. Tardio said a search committee already has narrowed the field for a successor to three to five finalists.

Tardio confirmed that he has talked to Manderfield "about the rumors" that Manderfield was interested in leaving First American. Manderfield has a reputation as one of the best bankers in the Financial General operation. A number of executives of Financial General banks are reported ready to resign if a group of Middle Eastern investors succeeds in its attempt to buy control of that company.

Surburban's announcement said Boatwright "will leave the bank by the end of the summer." No disclosure was made whether any financial settlement was given to secure Boatwright's resignation.