If you have previously dualboot your Windows 7 and Vista and now you wanted to remove it, either because you don’t like it or you are running out of hard disk space, here is the way to do it:
Remove the Windows 7 boot entry
Previously when you install Windows 7, it modifies the bootloader and makes it the default OS to boot up. If you are going to uninstall Windows 7, you will have to remove the entry from the bootloader so that you don’t have any conflicts when booting up later.
Download and install EasyBCD.
Run EasyBCD. On the left pane, click on the Add/Remove Entries.
On the right pane, highlight the Windows 7 entry and click Delete.
Download GParted iso file and burn the image to a CD.
Boot up your computer with the Gparted live CD. On the main screen, you should see your Windows Vista and Windows 7 partitions.
There are two ways that you can deal with your Windows 7 partition:
1) reformat it and use it as an additional partition to your Vista partition
2) remove the partition and return the extra space back to the Vista partition
Reformat Windows 7 partition
Highlight and right click on the Windows 7 partition. Select Format to -> ntfs.
Remove Win 7 partition and return it to Vista partition
Highlight the Windows 7 partition and click the Delete button.
Next, highlight the Windows Vista partition and click Resize/Move. Increase the New Size to the maximum. Make sure that the Free Space Preceding and Free Space Following is zero.
Once all the operations are completed, exit GParted and restart your computer. You should now boot into your Vista. Depending on the option you choose, you will have either a new blank partition that you can use to store data or a bigger Vista partition.
That’s it. Enjoy!