Well, this is what I could figure out about it:
Requirements: Your moms (or whoever of your parents installed it.) Windows Live ID (with password.). So, wrestle it out of her, and you're good to go!
Step 1:
a. In Windows 7 or Windows Vista, click the Start button, and then click in the Start Search box.
-or-
In Windows XP, click Start, and then click Run.
b. Type appwiz.cpl, and then press Enter.
c. Click Windows Live installer, and then click Uninstall/Change or Change/Remove.
If you're prompted, click Continue.
d. Select Uninstall, and then click Continue.
e. Select Family Safety, and then click Continue.
f. Follow the on-screen instructions.
g. After the Family Safety Filter has been uninstalled, restart the computer.
Step 2:
On any computer, sign in to the
Family Safety home page with the
Windows Live ID of the primary parent (the parent who installed Family Safety).
Step 3:
Under
Your computers, click
Remove computers from this list.
Step 4:
Click
Remove a family member, and then select Remove next to the name of the primary parent.
When you remove the primary parent, the entire family is removed.
Step 5:
Next to the name of the computer you want to remove, check
Remove, and then click
Save.
Seems there is no other way, than by having the Windows Live ID.