Hi
kiran.hrjavaji Thank you for your asking. Please try following steps to access recovery mode for the Factory Reset:
0. Try to back up your data with USB cable
1. Power off the phone, then keep pressing "volume down key"
2. Press "power key" and stop press " power key" once you feel the vibration
3. Still keep pressing "volume down key" and stop press "volume down key" once you enter [Android Recovery] Screen
4. Choose "Wipe data/factory reset">"Factory data reset"
5. "Reboot system now"
#Hardware Reset Guide
https://www.asus.com/support/FAQ/1006346/Please note that once the steps is completed, all data, apps, settings and personal information will be deleted.