code: function(provider) {
          if (!this.isCurrent()) {
            return;
          }
          if (_.isString(provider)) {
            provider = AV.User._authProviders[provider];
          }
          if (provider && provider.deauthenticate) {
            provider.deauthenticate();
          }
        }
docs: Deauthenticates a single provider (e.g. removing access tokens from the
  Facebook SDK).
  @private