Changing XBee module from AT mode to API

I recently Bought two XBee-ZB modules. one is cordinator and the other one end node. Both these modules are currently in AT mode. I want to change these modules to API mode. I am using X-CTU v6.1.0. How to perform these changes?

Use the XBee Recovery function on the Tools menu to select the desired function set and version. Then write it to the module.