If you need to remove someone from your Microsoft family, it's important that you first turn off all family settings for anyone labeled as a Child, or some settings may still apply.
Note
You can be an adult, but still be in the Child role, so it's best to double-check on your family roster page. It says your role under each person's name.
Online
To remove someone, go to account.microsoft.com/family and sign in with your Microsoft account. Then:
To remove a child, find their name, select More options > Remove from family.
For adults, select Remove from family under the name of the person you’re trying to remove.
If you’re the only adult in the family and wish to leave, you’ll need to remove all kids first, then find your name and select Leave family.
On Xbox One
You can also remove members from your Microsoft family on Xbox One, but as noted above, it's important that you first turn off all family settings for anyone labeled as a Child in your Microsoft family. On your Xbox One:
Sign in with an adult account on the console.
Press the Xbox button to open the guide, then select Settings > All Settings > Account > Family.
Enter a password or passkey to authorize the change.
Select the account you want to remove, then select Remove from family.