WARNING - YOU WILL WIPE OUT YOUR CURRENT SETUP. ALL SETTINGS AND ENROLLMENTS WILL BE LOST
If you want to just reload the virtual machine and start again.
Close the virtual machine down. Start/shutdown
Go to the documents folder in the host system. There should be a folder called Virtual Machines
Go into that folder. There should be a compressed file called Windows XP Professional-HideAccessCode or it may be just Windows XP Professional
Delete the folder called Windows XP Professional (careful not to delete the compressed file if it is named the same as the folder)
Once the folder is deleted, right click on the compressed folder and select Extract Here
It should reload the virtual machine in the right folder.
After extraction, you should be able to restart the virtual machine and begin doing your setup and enrollments.