To Uninstall Ubuntu from a Windows 8 dual boot is very simple using EasyBCD 2.2 program.
Uninstall Ubuntu from a Windows 8 Dualboot:
1. You’ll need to download and install EasyBCD 2.2.
2. Once installed run the program and click on BCD deployment from the left menu.
3. Make sure under BCD Deployment that the radio button for windows Vista / 7 system is checked.
4. Then click on Write MBR. when finished Click on Edit Boot Menu.
5. To the right of Windows 8 Place a check mark to the left side of yes under Default.
Reclaim your hard drive space:
1. Right click Computer from the Desktop then select Manage from the context menu.
2. Click on Disk Management
3. Now delete Linux / Ubuntu partitions.
Note: Make sure to delete only the Known Ubuntu partitions, otherwise you may lose some data you did not intend to lose.
4. To delete the partition either click on the partition and press the delete key or right click on it and select ‘Delete Volume’
5. Once the volumes, that were previously for Linux, are deleted you will be left with a big green area that is listed as ‘Free Space’
6. Select the green area and delete it, you will be left with Unallocated Space
7. Right click on your Windows volume and select ‘Extend Volume’, follow all the defaults (keep clicking ‘Next) and when you’re done you’ll have one big Windows partition.