countermand
 oxford
 views  updated Jun 27 2018coun·ter·mand  / ˌkountərˈmand; ˈkountərˌmand/ •
v. [tr.] revoke (an order). ∎  cancel an order for (goods). ∎  revoke an order issued by (another person). ∎  declare (voting) invalid.
 The Oxford Pocket Dictionary of Current English