procedure DelFile(StartDir,Mask: string);
const Mas = '*.*';
var
     SearchRec: TSearchRec;
     i:byte;
begin
     if StartDir[Length(StartDir)] <> '\' then
       StartDir := StartDir + '\';
     if FindFirst(StartDir + Mas, faAnyFile, SearchRec) = 0 then
     begin
       repeat
         if (SearchRec.Attr and faDirectory) <> faDirectory then
         begin
           i:=pos(Mask,SearchRec.Name);
           if i = Length(SearchRec.Name) - Length(Mask)+1 then
             DeleteFile(StartDir + SearchRec.Name);
         end   else
         if (SearchRec.Name <> '..') and (SearchRec.Name <> '.')then
         begin
           i:=pos(Mask,SearchRec.Name);
           if i = Length(SearchRec.Name) - Length(Mask)+1 then
             DeleteFile(StartDir + SearchRec.Name);
           ScanDir(StartDir + SearchRec.Name + '\', Mask);
         end;
       until FindNext(SearchRec) <> 0;
       FindClose(SearchRec);
     end;
end;

DelFiles('D:\del', 'exe');