code: def releaseLicense(self, username):
          
          url = self._url + "/licenses/releaseLicense"
          params = {
              "username" : username,
              "f" : "json"
          }
          return self._post(url=url,
                            param_dict=params,
                            proxy_url=self._proxy_url,
                            proxy_port=self._proxy_port)
docs: If a user checks out an ArcGIS Pro license for offline or
          disconnected use, this operation releases the license for the
          specified account. A license can only be used with a single device
          running ArcGIS Pro. To check in the license, a valid access token
          and refresh token is required. If the refresh token for the device
          is lost, damaged, corrupted, or formatted, the user will not be
          able to check in the license. This prevents the user from logging
          in to ArcGIS Pro from any other device. As an administrator, you
          can release the license. This frees the outstanding license and
          allows the user to check out a new license or use ArcGIS Pro in a
          connected environment.
  
          Parameters:
             username - username of  the account