I installed Ubuntu 17.04 on a 128gb USB drive. I followed an online tutorial to ensure that everything was installed on the USB drive and nothing on my laptop HDD. Well, somehow grub was installed onto my hard drive and overwrote the windows bootloader even though for the bootloader partition I choose to instal on the USB. Anyway, now at every boot I have to choose my os, not that that in itself is bad but ubuntu wont even boot and I want to get rid of it all completly. Can anyone help with removing grub and getting the windows bootloader back.