Do I need to delete all partitions when doing Clean Reinstall ?

I'm so sorry AddRAM . I just tried it Don't be mad
Ok I'll delete it because it's premature, just testing it .

If your friend gave you a copy of Win8 which he said would activate through KMS servers then it was Enterprise which must have had a key available or it wouldn't activate through KMS servers.

But unless he assures you this is his business offering you a key to activate from his account, then it's best you should delete Win8 now. This gives you space to Extend both C and D if you want: Partition or Volume - Extend

or let us know if you'd like to distribute the unallocated space otherwise and we will give you the steps using Partition Wizard Resize Partition Video Help.