I have two iCloud accounts under two different ids

I apparently have two iCloud accounts - one with my family sharing id and iCloud id on all my current devices. I have another account under an id I only use for purchases and apparently for accessing my subscriptions on this website. For instance, when I look at the devices offered to me for this post, the old devices are shown - not my current devices. The second iCloud account was probably from an old device and it is full. Is there anyway to get rid of it? I know there's no way to get rid of the second id, but that's really what I'd like to do as I believe it is confusing my devices talking to each other (like for Apple Music).