Win 8.1

Hello
I just installed 8.1 from the 8.1 disc with the generic key then activated with my 8 key. I looked in disc management and saw this extra partition, E:.

Do I have to leave it there or can it be deleted and if so how do I do it.
I wish to have the reserve and C: only if possible.
Thank you
Peter

Do you have a disc in the tray or an image mounted somewhere?

I have nothing in the cd trays and I do not understand about mounted. Could you please explain what I have to do?
This second pik is from This PC. As you can see only MY Book is connected for back ups.
I will check disc management again.
Thank you

I rechecked disc management and the drive that shed before has disappeared. I hope all is ok.

E: was a UDF file system which is for Optical CD/DVD drives, not hard drives.

E:

The bad was I likely looked at disc management with the installation disc in. The good is the Win 8.1 disc made with an iso from a friend and my 8 key worked well. Thank you