Sign out button greyed out? Follow this guide to re-enable the Apple ID sign out option.
If you are not using Family Sharing, complete the following step on your child’s iPad:
Go back to the Apple ID section and the Sign Out option should no longer be greyed out.
Once your child has signed in to their CEWA Apple ID, you will most likely want to re-enable Screen Time to continue restricting the iPad. To re-enable Screen Time, Apple has created a guide here: https://support.apple.com/en-au/guide/ipad/ipadb15cb886/ipados
If you are using Family Sharing, complete the following steps on your (parent) iPhone: