Release of memory from offline storage

[jirams]

IOS 8.4 on iPad and iPhone

I have several albums downloaded for offline listening.  Lets say for example they are Albums A, B and C and that they each use up 1.5 gB on my device (big I know).  Therefore there is 4.5 gB of memory allocated to Spotify files on the device.

Now, I no longer wish to store Album B.

How do I selectively remove Album B from device memory and still leave Albums A and C using up only 3 gB now?