%symdel can be used to undefine/delete a macro variable. %let some_var = foo; %put some_var = &some_var; /* some_var = foo */ %symdel some_var; %put some_var = &some_var; /* WARNING: Apparent symbolic reference SOME_VAR not resolved. */ %symdel some_var; /* WARNING: Attempt to delete macro variable SOME_VAR failed. Variable not found. */ %symdel some_var /nowarn;