Hello,
According to the Microsoft Family Safety policy, only the Organizer of the family safety group can add or remove members.
If the organizer's account is not accessible, you will have to use the Account Recovery form here to recover the account:
For reference, see:
How to leave a Microsoft family group
If the organizer's account is unknown or cannot be recovered, contact Microsoft Support through live chat and ask whether they can help remove your account from the Family Safety group.
https://support.microsoft.com/en-us/home/contact
- Type Talk to an agent, then click Get Help.
- At the bottom of the page, click Contact Support. Sign in to your Microsoft account if needed.