Pascal/Turbo Pascal - necesito que la entrada de clave se pueda usar la tecla de borrar

como puedo hacer para que el cliente pueda borrar sio sabe que ingreso mal la contaseña?




Procedure LECTURACONTRA (OPC:char);
var
ch:char;
password, CLAVE: string;
cont:integer;
begin
ClrScr;
cont:= 0;
if (OPC='1') then
begin
CLAVE:='EMPRESA123';
repeat
write('Ingrese la CLAVE de ACCESO EMPRESA: ');
ch:= readkey ;
password:='';
while (ch<>#13) do
begin
if ch<>#8 then
begin
password:=password+ch;
write('*');
ch:=readkey; end
else
Delete(password,Length(password),1);
write('');
end;
if password = CLAVE then
begin
ClrScr ;
Gotoxy (24,02); Write ('+----------------------------------+');
Gotoxy (24,03); Write (': ACCESO CORRECTO :');
Gotoxy (24,04); write (': :');
Gotoxy (24,05); Write ('+----------------------------------+');
Delay (1100);
ClrScr ;
MENUEMPRESA;
end
else
begin
cont:=cont+1;
ClrScr ;
Gotoxy (24,02); Write ('+----------------------------------+');
Gotoxy (24,03); Write (': CONTRASEnA INCORRECTA :');
Gotoxy (24,04); write (': INTENTO NUM: ',cont,' :');
Gotoxy (24,05); Write ('+----------------------------------+');
password:='';
Delay (1000);
ClrScr ;
end
until (password='EMPRESA123') or (cont=3)
end;
if (OPC='2') then
repeat
write('Ingrese la CLAVE de ACCESO CLIENTE: ');
ch:=readkey;
password:='';
while (ch<>#13) do
begin
password:=password+ch;
write('*');
ch:=readkey;
end;
if password = 'CLIENTE123' then
begin
ClrScr ;
Gotoxy (24,02); Write ('+----------------------------------+');
Gotoxy (24,03); Write (': ACCESO CORRECTO :');
Gotoxy (24,04); write (': :');
Gotoxy (24,05); Write ('+----------------------------------+');
Delay (1000);
ClrScr ;
MENUCLIENTE_ING;
OPC:='0';
end
else
begin
cont:=cont+1;
ClrScr ;
Gotoxy (24,02); Write ('+----------------------------------+');
Gotoxy (24,03); Write (': CONTRASEnA INCORRECTA :');
Gotoxy (24,04); write (': INTENTO NUM: ',cont,' :');
Gotoxy (24,05); Write ('+----------------------------------+');
password:='';
Delay (1000);
ClrScr ;
end
until (password='CLIENTE123') or (cont=3);
end;