You can use the following steps to reset your tablet in the boot status.
1) Go to “Settings”.
2) Touch “System”
3) Touch “Reset”.
4) Touch “Factory data reset” to start.
5) Touch “RESET DEVICE” in the open window.
6) Touch “ERASE EVERTHING”.
Warning: this action will erase all your personal information and downloaded apps.

Factory reset while your tablet is in in Shutdown state.
1) Power off the tablet. Long press the “power” key and “volume up” key until enter the Android system recovery mode.
2) Press the “volume” key to select “wipe data / factory reset”, then press the “power” key to confirm factory reset;
3) Press the “volume” key to select “Factory data reset”, then press the “power” key to confirm the deletion of all user data;
4) When the factory reset is complete, press the “volume” key to select “reboot system now” then press the “power” key to confirm.