Thanks for the reply. So, it is an icon of your internal drive (or at least one partition on it). Just to confirm, when you double click on it, what does it show? I suspect it will show the "initial" 5 folders (Applications, Library, System, Users, Documents). Most people prefer to have it there, so that one can get easier access to items on the drive.
If you want to get rid of it, in the Finder, click on the "Finder" heading (just to the right of the Black Apple one). Then, select Preferences. You will see a "list" of devices, along with a "box" to the left on each one. Assuming High Sierra is like Sierra (hat is the OS I am using), the first one on the list is "Hard Disks". Myself, I have it checked, but if you don't want on your desktop, then uncheck it.