There is a hidden account named administrator on Windows.Most of the time,the account has no password if not set before.
So,it makes clear that you can start your computer with Administrative account.After starting go to control panel to delete or change the password of any users and by doing that you can fix your problem easily
To do so,you are to do the following steps:
At first boot your computer and immediately press on the F8 key repeatedly until you can see the boot menu on your computer display.
Choose SAFE MODE with the arrow keys and press ENTER key.
Click on ADMINISTRATOR then on home screen
IF you don't have any HOME SCREEN,type Administrator and leave the password as balnk.
Click on the START menu in the bottom left corner,then go to the control panel and go in USER ACCOUNTS,there you can change any user password you desire.
Peace be upon you