PiPO M8HD - Manual (Page 42)

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6. How to delete a Google account?
If an account is added, the account is shown in ―Accounts & sync‖ of ―Settings‖,
where you may also add another account. To delete an undesired account, go
to ―Settings‖ → ―Privacy settings‖ → ―Factory data reset‖. Your tablet‘s internal
storage, downloaded apps, etc. will also be deleted, except the info in your
flash memory. Be careful before you carry out this operation.
7.USB unmounted, SD card unmounted
Some times after inserting SD card or USB, it will show on the tablet that
―unmounted‖, do the factory reset by ―setting‖ – ―backup & factory reset‖, and
then turn off and turn on tablet once again. If fail, you have to upgrade the
firmware.