A full extension drawer slide has three-piece telescoping slide hardware that glides on ball bearings. The fixed portion of the slide -- which is constructed of two metal rails -- is mounted on the inside edges of the drawer opening on the cabinet. The remaining rail of the three-piece unit is mounted to the outside edges of the drawers. When the drawer is inserted into the opening, the rails lock together so that when the drawer is pulled out it will not continue and spill the drawer contents.
This type of full extension slide uses release buttons to remove the drawer from the slide. Once the drawer is pulled out of the cabinet fully, these release buttons should be visible on the outer edges on each of the drawer slides. Push in on the release buttons while pulling out on the drawer. There will be a slight resistance, but the drawer should slide right out.
Some full extension slides require a release tool to remove the drawer. The release tool should come with the slides. Pull the drawer out of the cabinet fully to expose the outer edge of the slides. The spring-loaded release tool has a square end and a handle. Insert the square end of the tool into the gap between the outer and inner slide rails. Raising the handle of the tool upwards while pulling out on the drawer slightly should release it from the side hardware. This needs to be performed on each side of the drawer.
Push the slides mounted to the cabinet back into the drawer opening before installing the drawer. Insert the slide hardware mounted on the side of each drawer into the slides in the cabinet. Once the drawer is pushed all the way back in, it should lock into place.