Hi,
I had to think a while to try and work out a way of getting round this little boob. I assume you don't want to re-install or that the system arrived with windows already installed so you could try this.
Place the cursor over to the bottom right of the screen so the 'Charms' appear and then click the cog wheel or settings charm. On the bottom of the revealed section click 'Change pc settings'.
Look down the left hand side for 'Users' and click that. Hopefully on the next screen, near the top, you'll see 'switch to a local account'. Try doing that and then removing the original account via the control panel, User accounts, and then add and remove user accounts.
If it works then you might have to follow the first process again but this time switch to a microsoft account making sure the details are correctly filled in.
Post back if this doesn't work and we'll try something different.