I have a Win7-Ubuntu16.04 dual-boot non-UEFI laptop. I'm planning to downgrade my Ubuntu to 14.04 LTS after having a problem with 16.04 not booting properly. I don't have important files in the Ubuntu partition to worry about so I'm thinking of outright deleting it with the Windows Disk Manager, and afterwards boot to a live 14.04 disk and install from there.
On top of this, I'm not planning on restoring the Windows boot loader (since I can't, anyway. CD drive broken). So unless 14.04 installs correctly or at least a new grub is put in place, then probably goodbye Windows as well.
I just want to know if what I'm about to do is perfectly, definitely OK. What are the odds of 14.04 not installing successfully or booting in the first place? I'm using Rufus to burn the ISO into a USB drive.