How to delete GRUB entirely from GRUB rescue and boot Windows only

Assuming you are using Windows 7 (this should also work on Vista and Windows 8):

1. Put the Windows 7 installation/Upgrade disc in the disc drive, and then start the computer (set to boot from CD in BIOS).

2. Press a key when you are prompted.

3. Select a language, a time, a currency, a keyboard or an input method, and then click Next.

4. Click Repair your computer.

5. Click the operating system that you want to repair (Windows 7 in this case), and then click Next.

6. In the System Recovery Options dialog box, click Command Prompt.

7. Once in the command prompt, type exactly Bootrec.exe /FixMbr and then press ENTER. You will see "operation completed successfully." (Doesn't even take a second. Don't be alarmed )

8. Reboot and set BIOS to boot from the HDD again.

GRUB will be overwritten in step 7 and Windows bootloader will once again take control of loading your OS(s).

Source

I don't if its possible to get rid of grub entirely, and boot just windows (without simply reinstalling windows), but you can fix your grub - just get an ubuntu live cd (or USB) and use Boot-Repair - the 2nd option listed at https://help.ubuntu.com/community/Boot-Repair

Start windows recovery follow the instructions to get to a command line prompt, then type

BootRec.exe /fixmbr  

reboot and you're all good to go.

Assuming your partitions are still in order, you can fix the MBR in Windows Recovery and it will boot back into Windows.

http://support.microsoft.com/kb/927392

If you do have an Ubuntu partition, it won't be wiped so you might need to do additional clean up no your partitions afterwards.

Put the Windows 7 installation/Upgrade disc in the disc drive, and then start the computer (set to boot from CD in BIOS).

• Press a key when you are prompted.
• Select a language, a time, a currency, a keyboard or an input method, and then click Next.
• Click Repair your computer.
• Click the operating system that you want to repair (Windows 7 in this case), and then click Next.
• In the System Recovery Options dialog box, click Command Prompt.
• Once in the command prompt, type exactly Bootrec.exe /FixMbr and then press ENTER. You will see "operation completed successfully." (Doesn't even take a second. Don't be alarmed )
• Reboot and set BIOS to boot from the HDD again.

GRUB will be overwritten in step 7 and Windows bootloader will once again take control of loading your OS(s).

Then load your bootable pen drive or CD so,your your problem will be solved.

All the best!