Widraz
You don't have to uninstall it, you'll have to use the whole disk. There's an option in the installer that essentialy says "Erase everything and use the whole disk for Solus" (don't remember the exact wording but it's there).
The installer will make the rest.
If you know what you're doing you could run Gparted from a live USB, do whatever you want with the disk, and then install to a blank slate