A true untethered iCloud removal (where the device is permanently disassociated from the previous Apple ID) does not exist for iOS 9.3.5. However, an untethered activation bypass does exist. This allows you to use the iPad normally (Wi-Fi, apps, camera, games) as if it were a new device, with the sole exception that you cannot sign into the original owner’s Apple ID.
mount -o rw,remount / cd /mnt1/Applications/ mv Setup.app Setup.bak Use code with caution. Type reboot to restart the device. ipad 2 935 icloud bypass untethered