If you want to delete all data on /dev/sda2, you must delete the volume group SolusSystem and the physical volume associated via the following lvm commands :
sudo vgdisplay (display the volume group properties SolusSystem)
sudo vgremove -y SolusSystem (delete the volume group SolusSystem)
sudo pvdisplay (display the physical volume properties, including /dev/sda2)
sudo pvremove -y /dev/sda2 (delete the physical volume /dev/sda2)
Then you will be able to delete/format the /dev/sda2 partition via gparted. After reboot the reinstallation would be ok.
