I tried to set up my UM 16.04 installation to boot without going through a Grub menu. If I ever wanted to boot a different hard drive, I would simply select it using the bios menu. So I installed 16.04 with no other hard disks attached. Once installed I re-attached my other drives. All worked fine until the first UM update. After the update and mandatory reboot, I am now presented with a Grub menu.
My current configuration is as follows:
sda: XFS, non boot
sdb: Ext4, Ubuntu Mate 16.04
sdc: Ext4, non boot
sdd: Ext4, Ubuntu 12.04
Is a grub really needed. How can I safely remove the grub?