A method comprises the steps of providing a tool over a collar secured to a stud on a gas turbine engine system. The collet is driven to rotate and remove the collar from the stud. A tool for removing collars from studs has a driver with a housing receiving a piston. A spring drives the piston, and the housing also has a hydraulic fluid supply opening for selectively receiving a hydraulic fluid to move the piston in opposition to a force from the spring. Collet fingers are movable between a released position and a secured position when a supply of hydraulic fluid is supplied into the housing.