The following is how to "Hard Reset" a device. You should also find the option, when done correctly, to reset it without wiping everything (although a full wipe is the only way to make sure nothing unwanted remains). If your device will not allow for using these instructions, then there may be something wrong with the buttons, or the device was rooted and would need to be unrooted first.
NOTE: Doing this will clear 'all' the data on your tablet, so it is suggested you not choose this option unless you have to, or aren't worried about losing anything on the device.
Be sure you back up any data you want to keep, to a computer or cloud account, before doing the reset.
To "Hard Reset" the tablet...
1. Make sure that the tablet is...