Force factory reset iPad
My iPad is not factory resetting for anything
iPad Pro 11-inch Wi-Fi
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See these support articles:
Restore your iPhone, iPad, or iPod to factory settings [with a computer] - "A factory restore erases the information and settings on your iPhone, iPad, or iPod and installs the latest version of iOS or iPod software." - http://support.apple.com/HT201252
How to erase your iPhone, iPad, or iPod touch
"Learn how to wipe information from your iPhone, iPad, or iPod touch and restore your device to factory settings." Without using a computer. Does not reinstall iOS.
https://support.apple.com/HT201274
If neither of the above work, read the "If you can't erase your device" section in the last link, including the last part about contacting Apple.