Steps

1. Charge iPhone or iPad more than 50%
2. Download and install the latest iTunes version
3. https://www.apple.com/fr/itunes/
4. Disconnect iPhone or iPad from PC or Mac
5. Put the iPhone or iPad in DFU mode (recovery mode)
6. https://www.youtube.com/watch?v=2Idm4IUOAyU
7. > If it is an iPad Pro 2018 (with Face ID):
8. Press and release the "Volume +" button
9. Press and release the "Volume -" button
10. Press and hold the "Power" button until the iPad screen turns black
11. Continue to press the "Power" button, and hold the "Volume -" button at the same time for at least 5 seconds
12. Release the "Power" button, but hold the "Volume -" button for 10 seconds
13. An iTunes message will appear on your computer screen saying "iTunes has detected an iPad in recovery mode. You must restore this iPad before it can be used with iTunes "
14. > If it is a normal iPad (with main button):
15. Press both the "Power" and "Home" button for 10 seconds
16. Release the "Power" button, continue to hold the "Home" button until iTunes reminds you "iTunes has detected an iPad in recovery mode..."
17. Connect iPhone or iPad to PC or Mac
18. A window will appear saying "iTunes has detected an iPhone (or iPad) in recovery mode. You must restore this iPhone (or iPad) so that it can be used with iTunes."
19. Accept and start the manipulation (this will install the iOS denier and put it back the same on the first day)
20. /!\ It may take several minutes