code: function(xtype) {
          var me = this;
  
          if (Ext.isArray(xtype)) {
              Ext.Array.forEach(xtype, me.removeXTypeFromWhitelist, me);
              return;
          }
  
          Ext.Array.remove(me.whitelist, xtype);
      }
docs: Removes the specified xtype from the {@link #whitelist}.
  @param {String/String[]} xtype Removes the xtype(s) from the {@link #whitelist}.