Here is what you need to do:
- Burn an Ubuntu ISO image onto a USB Drive or a DVD to make a Live USB/DVD.
- Boot into Live mode ("Try Ubuntu" option).
- After it boots up, press "Ctrl + Alt + T" to bring up the Terminal.
- Put these codes ONE AFTER ANOTHER.
sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install boot-repair
After doing this, open the "Dash" (Search menu). It can be accessed by "Alt + F2"
Search for "Boot Repair" (Although just entering Boot will give you the app).
Open it and select the only option (Recommended one).
Reboot. You will no longer get the GRUB Error after this, and will boot straight into Windows.
You can also do it with Ubuntu installed. In case you want to Uninstall ubuntu, first follow the above instructions, then after you are in Windows, install EASUS Partition Manager and delete the Ubuntu partitions (the ones that are NOT ntfs formatted)