I’m not a big fan of the Nautilus file app, but it’s ok. On the left side it shows certain folders, location bookmarks, and mounted disks. If you want to hide or change the way they’re displayed, open up the Disks app. Find and select the partition you’re adjusting and click the gear button and choose “Edit Mount Options”. On the dialog that pops up, disable “Automatic Mount Options” at the top. Then look for the checkbox that says “Show in user interface”- uncheck that to hide the disk in Nautilus. You can also adjust what the disk’s label will be under “Display Name”. When you’re done, click OK to apply the changes.

Thanks to http://askubuntu.com/a/232754/95754 for the tip.

Due to a bug in the Disks app, you should not use the “Show in user interface” checkbox to start having a disk show up. If you do, it adds a mount option

 x-gvfs-show

to /etc/fstab which at least in the current version of Ubuntu will throw errors when mounting. What it actually needs to be for now is:

comment=x-gvfs-show