Used ubuntu to get into back to Windows and want to remove

Used ubuntu to get into back to Windows and want to remove

As a medical resident, my wife was given a laptop to use for work. Upon
graduation, she was able to keep the computer and their IT deleted all the
hospital files, etc and were supposed to give her permissions but they
never supplied a boot disk. The computer is hers; we aren't pirating or
stealing. They never supplied the password and we were locked out of
Windows 7 during the first update. We used Ubuntu to be able to get back
into the computer by changing the password through the utilman and cmd
executable files. Now the laptop has the Grub start up and is further
partitioned from the install. How do we remove the Ubuntu and Grub and
just use Windows without a Windows boot disk? Thank you