Question: how to delete gdg versions in jcl?
Answer: DELETE ALL GDG VERSIONS WITHOUT DELETING BASE.
Below JCL would delete all the versions of the GDG without deleting the BASE.
//PGM EXEC PGM=IEFBR14.
//YOURGDG DD DSN=YOUR.GDG.BASE,
// DISP=(OLD,DELETE,DELETE)