How do I factory reset the Yoga 2 Tablet (Android)?
If you are able to boot into Android, you can go to Settings->Backup & reset:
Select Factory data reset at the bottom:
Here you can check "Back up data before resetting", which will prompt you to back up to either your external sdcard (if you have one installed) or to Lenovo's SyncIt app (if you don't have an external sdcard card). Otherwise, you check "Format internal SD card" to procede directly to the reset without backing up. Make your selection, then tap the Reset tablet button to perform the reset (and optional backup if you selected the first option).
If you are unable to boot Android, you can still perform a factory reset from recovery. Power off the tablet. Then power the tablet back on while holding down both the Power and Volume Up buttons. You will see the "Droidboot" menu:
At the "Droidboot" menu, use the Volume Up and Down buttons to highlight "Recovery" in yellow, then press the Power button to select it. The tablet will reboot into recovery. In recovery, you'll be prompted to select a language (English or Chinese), then you will reach the recovery menu:
Tap "wipe user data" here to perform the factory reset. When it finishes, tap "reboot" to reboot into Android.