How to remove Ubuntu and put Windows back on?
To remove Ubuntu, you will need a Windows Recovery CD or Installation CD, or a Ubuntu Live CD.
Note: If you don't have a Windows Installation or Recovery CD available, you can download the Windows 7 ISO file (contact Digital River customer support as said in Microsoft help page ). You cannot install Windows without a genuine Purchased Product Key though, as these ISO files are 100% legal and will only install as an Evaluation copy for 30 days without a product key.
To remove GRUB:
Grab a Windows recovery media or installation CD and boot from it. You should see this on a recovery media CD.
And you should see this on an installation media CD. Click "Repair your computer" and you should see a screen like the first image.
Open the Command Prompt, then type bootrec /fixmbr into the Command Prompt.
Reboot and boot into Windows. Then
follow the steps below to remove the Ubuntu partitions.
(Images from HowtoGeek )
If you don't have a Windows recovery CD or you are constrained to download and burn the ISO files mentioned before, you can use Boot-repair. It is a tool that fixes most boot problems(Windows or Ubuntu). I suggest using a Windows CD if possible.
Boot from a Ubuntu live CD or USB
Type these lines in the terminal one line at a time.
Search for Boot-Repair in the Dash and launch it.
To fix your computer with Boot-repair, simply click the "Recommended Repair" button. Then follow the steps below to remove the Ubuntu Partitions.
Go to Start, right click Computer, then select Manage. Then select Disk Management from the sidebar.
Right-click your Ubuntu partitions and select "Delete". Check before you delete!
Then, right-click the partition that is on the Left of the free space. Select "Extend Volume". Go through the Wizard and Finish it.