Apple ID Sign Out and change Country/Region button is greyed out
I'm trying to change my daughter's country/region on her iPhone but the option is greyed out and there is a text "the country/region for your Family is managed by ...". I'm not sure how I can change the settings on my own phone so that I allow her to change the country/region. The button for Sign Out is also greyed out with the text "Sign-out is not available due to restrictions" under it.
The phone is connected to Family Sharing and the account is a child account. Downtime under Screen time is the only restriction we have enabled in Family Sharing.
I've tried to disable Downtime and reboot but no luck in solving this problem.
Please help or provide advice on how we can disconnect the phone from the iCloud account and change the country/region.
Thanks!
iPhone 6