Is there is any way to reset zigbee externally?

I have 3 ZigBee modules.But I don’t known about there family type.I want to reset this modules ,by connecting external circuit to it.But I confuse to what I do in next step?
If anyone known about this please give me reply.

No Digi does not offer a way to Restore the radio to defaults using an external pin. That can only be done using the ATRE command via the radios UART.

without changing its configuration or any command in micro controller programming, it is possible to reset zigbee by using timer or other equipment?
If yes how to do this?

No, it is NOT possible to restore an XBee module to factory default settings using a Pin. The only way is to issue the ATRE and ATNR0 or 1 commands while in command mode.