I have unglued Multiple times pvc fittings. I find an old socket that will fit the inside diameter of the pipe with a little bit of gap. Heat the socket up not cherry red but good and warm. Put it in the fitting and using a flathead screwdriver I keep pressing the pipe away from the fitting until it is "rubbery" all the way around. Remove the socket and the use the screwdriver to work the pipe away from the fitting walls into the center. it will pull away from the fitting wall cleanly and then grab it with pliers and pull it out before it hardens. I have had bad glue joints with small leaks on spears gate vales and done this with absolutely no issue. I make sure to clean and prime the fitting well before I reglue.