So it looks like you have either a partition on your internal drive labeled that way, or an APFS volume. If you highlight the Storage volume, what does that say?
APFS = Apple File System. It's Apple's replacement for Mac OS Extended (HFS+). So you didn't mention what desktop you have, but I assume you should only have a single drive inside. You are running a much older version of macOS than I am, so Disk Utility displays things a little differently. If you have nothing stored on that Storage volume, you should be able to simply click the - button up on the menu bar where it says Volume to remove it. However, before doing so, I absolutely recommend doing a full backup of everything "just in case". But you should be good to go.
Many thanks for the input and suggestions. I've decided to keep the storage facility now that I understand it. Very useful. Upgrading my iMac shortly, as this one is, as pointed out, getting on a bit.