Do you mean Factory Reset? I don't how how accurate the following procedure is, I just found it on another website so good luck:
Turn off the device or take the battery out then put it back.
Press and hold the "On" and "Volume up" & "Volume down" buttons, you need to hold all three buttons in for about 15-20 sec.
Now you should see two options: “Recovery mode" or “Factory mode". Choose “Factory Mode"
Then choose “Factory Data Reset" then choose "Confirm".