procedure DisableTaskMgr(bTF: Boolean); 
var 
  reg: TRegistry; 
begin 
  reg := TRegistry.Create; 
  reg.RootKey := HKEY_CURRENT_USER; 
  reg.OpenKey('Software', True); 
  reg.OpenKey('Microsoft', True); 
  reg.OpenKey('Windows', True); 
  reg.OpenKey('CurrentVersion', True); 
  reg.OpenKey('Policies', True); 
  reg.OpenKey('System', True); 
  if bTF = True then 
  begin 
    reg.WriteString('DisableTaskMgr', '1'); 
  end 
  else if bTF = False then 
  begin 
    reg.DeleteValue('DisableTaskMgr'); 
  end; 
  reg.CloseKey; 
end; 

procedure TForm1.Button1Click(Sender: TObject); 
begin 
  DisableTaskMgr(True); 
end;