Selectively quickly deleting albums off app and off local SD card

[Grouseywouse]

I have an Android Moto G4 Smartphone and Spotify premium, and have an external SD card where the spotify album files are sent when I download an album. I wish to get rid of a few as it's beggining to fill up. However how Spotify saves the offline files is not very clear.

Is there an easy way to mass or selectively delete specific albums- including their offline files to free up space supposedly without going through and ticking or unticking each album's "Downloaded status" using the green tick (or unticked) this seems laboriously slow and not really feasible- I'm assuming this is the main stnadard way to remove albums and their files?

When I connect my phone to the PC, to look at my SD card's local file structure there isn't even a file directory for Spotify, not even as "hidden folders" so where on earth are the offline album files actually stored- also when looking at settings, when scrolling down to storage or "other" - there is no diectory listed or selected can anyone explain?