Question: Years ago i installed ubuntu on a hard drive in my computer. A few days ago, after the release of 18.04, i bought a ssd and reinstalled everything on that. The old hdd is still linked in the computer - just to look up things.

GRUB does index the old hdd as secondary boot option. But i will never ever boot the old system again. So is there any way to remove the old hard drive from the grub options?

Answer: 
I found my notes on this.

Edit `/etc/default/grub` and add the line

`GRUB_DISABLE_OS_PROBER=true`

Exit, saving changes, then run

`sudo update-grub`

From the grub [wiki](https://help.ubuntu.com/community/Grub2/Setup) (item 16)

> 
> This entry is used to prevent GRUB from adding the results of
>  os-prober to the menu. A value of "true" disables the os-prober check
>  of other partitions for operating systems, **including Windows, Linux,
>  OSX and Hurd**, during execution of the update-grub command. This will
>  keep grub from looking for other OS'es.
> 
> 
>
The easiest (GUI) way is to run **grub-customizer**

```
$ sudo add-apt-repository ppa:danielrichter2007/grub-customizer
$ sudo apt-get update
$ sudo apt-get install grub-customizer

```