Hello.
You can try this code
 %macro dirclear(dir=d:\test,ext=xls);
 %let ext=%upcase(&ext);
 %let dlm=\;
 %let filrf=;
 %let rc=%sysfunc(filename(filrf,"&dir"));
 %let did=%sysfunc(dopen(&filrf));
 %let lstname=;
 %let memcount=%sysfunc(dnum(&did));
 %if &memcount > 0 %then %do;
 %do i=1 %to &memcount;
 %let lstname=%sysfunc(dread(&did,&i));
 %let file=&dir&dlm&lstname;
 %let ln=%length(&lstname);
  data _null_;
  c="&lstname"; c1=reverse(c); ln1=index(c1,'.'); ln=&ln-ln1+2; ln3=ln1-1;
  ln4=upcase(substr(c,ln,ln3));
  call symput('ln2',trim(left(ln4)));
  run;
 %if &ln2=&ext or &ext= %then %do;
 %let rb=%sysfunc(filename(fname,"&file"));
 %let rv=%sysfunc(fdelete(&fname));
 %end; %end; %end;
 %let rc=%sysfunc(dclose(&did));
 %mend dirclear;
   %let path=%sysfunc(pathname(mylib));
  %dirclear(dir=&path,ext=png)