How To Unlink Permissions

To unlink an existing permission, submit a transaction to the unlinkauth action of the eosio account.

In the example shown below useraaaaaaaa unlinks the permissions present on the contract useraaaaaaaa's contract_action action.

const unlinkauth_input = {
  account: 'useraaaaaaaa',      // the permission's owner to be linked and the payer of the RAM needed to store this link
  code: 'useraaaaaaaa',         // the owner of the action to be linked
  type: 'contract_action'       // the action to be linked
};

(async () => {
  await api.transact({
    actions: [{
      account: 'eosio',
      name: 'unlinkauth',
      authorization: [{
        actor: 'useraaaaaaaa',
        permission: 'active',
      }],
      data: unlinkauth_input,
    }]
  }, {
   blocksBehind: 3,
   expireSeconds: 30,
  });
})();