If you can't leave the Microsoft Family group, first check your role and account status.
Go to https://account.microsoft.com/family and sign in with the Microsoft account that is showing the family group.
Find your name and select the three-dot menu.
If you see “Leave family group,” select it and confirm.
Microsoft notes that leaving the family group can also remove access to shared benefits such as Microsoft 365 Family.
If “Leave family group” is not available, you may be an organizer or the account may have age/consent restrictions. Organizers manage the other members, and some child/consent accounts require the organizer to remove them.
If you're an adult but Microsoft is treating your account as a child, check the birth date on the Microsoft account and follow Microsoft's Family Safety troubleshooting steps.
If the family group is not recognized or you still cannot leave it, contact Microsoft Support rather than creating another Microsoft account. Also, don't post your account email or other account details publicly.