I would right click on D: in disk manage and select "Change Drive letter and..." and remove a drive letter from the Reserved partition. It shouldn't have one assigned to it.
Next right click on the Disk 0- 930.43GB partition, select 'Change Drive letters' again and assign one to there. You can use D: if you want.
If you do want to format it then you'll have to use diskpart from the admin command window but firstl with the power off, disconnect the hdd sata cable and see if it does indeed boot only from the SSD. We can walk you thru using diskpart if you wish to go that route.