Inherited VM data disk setup query

Hi there,

I've inherited a VM in Azure:

OS Premium SSD disk of 127GB

4 x 4095 GB Standard HDD

In the VM the data drive totals 10.2TB with 7.6TB of space. I want to reduce the size but realize I can't, I'd have to create new smaller drives then move data to new drive letter in WIndows.

My confusion is why are there four identically sized disks? Also how do they only total 10.2TB when in the Windows partition manager there is no unallocated space?

Any suggestions if I've missed anything would be great.

THank you.