Phone locked due to family link

Hello, my son reset his phone while parental control was activated, it was asking to connect to the internet (impossible except on Wi-Fi networks never used before on the phone) and so I deleted the account directly from my phone. In the evening, he connects to my hotspot (which he had never used) and it works. He accepts the user agreements and then it requires signing into his Google account. We enter his "new account" and it says "log in with the email address of the previous owner of this account", we enter the email he had for parental control *******.*****42@gmail.com and it shows "email address does not exist", impossible to reconnect. Even Google France: 01 42 68 53 00 (Monday to Friday 9am-6pm) says it is closed even though it is Friday at 4:12pm (at the time of my call).

2nd solution Re-reset the phone therefore:
- Turn off the phone
- Turn it back on with the on/off button + volume up button + home button pressed together,
- Release the on/off button after the Samsung logo appears
- Choose Wipe data/Factory reset, then Yes and confirm with Power
- Once it’s finished, you will return to the general list, press Reboot system now

This solution doesn't work either and account recovery is impossible, what to do?