Galaxy Tab Pro 8.4 - How to Reset Back to Factory Settings | H2TechVideos
How to Delete All Data in SAMSUNG T520 Galaxy TabPRO 10.1 WiFi - Factory Reset in Samsung
Hard Reset SAMSUNG T520 Galaxy TabPRO 10.1 WiFi - How to restore tablet
Hard Reset will erase all of your data
All described operations you are doing at your own risk.