In pa if I terminate my rights to my child because there grandma wants to adopt them will I still have to pay support

If there is an actual termination of parental rights Order  of Court, validly entered by the Court, then you are no longer the child's parent.  Because you are no longer the child's parent, you don't have to pay child support.  Be aware though, that it's a complicated process to actually voluntarily terminate your parental rights.