Try this version. It is not quite the standard "Hard Reset" which is for standard Android tablets...
1. Turn off the tablet.
2. Next press "Power" and "Volume" at the same time until your tablet starts in "Fast Boot".
3. Now use the volume button to go to and select "Recover Mode".
4. Once it has been selected, press "Power" to restart the tablet into the Recovery mode OS.
5. Here you want to select "Wipe Data/Wipe Cache" and then select "Yes".
6. Once that is done, turn the tablet off and back on.