To unlock the bootloader you will need download the official tool from Asus support site. The device is entirely yours and ready to experiment. But the company warns that if something goes wrong and you have killed the device, the responsibility falls entirely on you. Add that using this utility, the user will never be able to return the device to its original state, even if there is a desire. Warranty service will be denied.
If you once bought to myself Asus Zenfone 2, as well as love all sorts of modifications to the system, then today's news for you. Asus officially allowed to open the bootloader of the device. However, we advise you to update the firmware to V220.127.116.11 before this procedure.