Boston technology services firm Keane Inc., still recovering from the resignation of a chief executive accused of sexual harassment, yesterday said it had fired the executive many on Wall Street had expected to succeed him. The company said it dismissed Richard S. Garnick , its president of North American services and global business lines, for ``just cause" relating to unspecified travel expenses and unauthorized communications. In a statement, Keane said it would not release details of the incidents because it was a personnel matter. Interim chief executive John J. Leahy last night said he made the decision to terminate Garnick, effective immediately, after consulting with lawyers inside and outside the company. The lawyers and Keane's board of directors agreed Garnick's actions ``had the potential to be very damaging to the company and its shareholders," said Leahy, though he would not discuss specifics.