To be able to Uninstall Windows XP, you must meet the following Requirements:

[Note:  If you upgraded from Windows NT , Windows 2000, or Windows XP Home Edition, You cannot Uninstall Windows XP.    You can remove XP and reinstall a diff operating system, however, you would lose all files and programs]

Restart Your Computer In Safe Mode.   To do this, tap the F8 key on your keyboard while the computer is booting up.  If you did it correctly you will see the following screen:

Use the up arrow key and select “Safe Mode”.  Then  the login screen will come up.  Log on with an account that has Administrator Permissions.

[Note that Windows XP during installation creates a default Admin, named "Administrator”, so if you are not able to login as an Admin, try using “Administrator” for username and leave the PW blank and click “OK”.  If this does not work then that means that during the installation a Password was applied to the Administrator Account by the person who installed Windows XP, so the only way to continue trying to Uninstall, would be to get the password from the person who installed it.  If you cannot, then you will have to Reinstall Windows, which will cause you to lose all your files and installed programs.]