HADLEY — After more than a decade as treasurer and 2½ years as Hadley’s first finance director, Linda Sanderson is retiring from both positions. The Select Board on Wednesday voted unanimously to accept Sanderson’s retirement, and afterward named Dede Dibrindisi, the assistant treasurer, to the permanent treasurer position. First elected by voters in 2015 to a position that has since become appointed by the Select Board, Sanderson will conclude her employment next week, though she anticipates being available to provide assistance. Sanderson’s job has expanded to preparing budgets and explaining details of spending to both the Select Board and Finance Committee, as well as on the floor of Town Meeting. “I’ve always been happy to work with this town so I don’t really want to leave it,” Dibrindisi said.