The easiest way is to add a new account in Windows. This is done as follows:
- Make a backup of your personal files.
- Go to Start --> Settings (cogwheel) --> Accounts.
- Click under 'Family and other users' on Add someone else to this PC.
- Click on 'I do not have this person's credentials'.
- Click on 'Add user without a Microsoft account'.
- Enter a name and possibly a password.
- Click on this new account and click on 'Change account type'. Make it Administrator and click 'Ok'.
- Log out of the temporary account via Start --> [account name] --> log out.
- Log in to the new account.