unsaved songs in library

[Jackxue]

Plan

Premium

Country

Canada 

Device

iPhone Xs Max

Operating System

iOS 12

My Question or Issue

normally when I save music, I go by:

artist-album-select songs I like-save-library-album-download.

this way i can download only the music i want. 

today i noticed that when i go in to the library-album, all albums show full songs (downloaded ones have a green arrow).

How to get rid of the songs that i don't like from ablum in the library?

(although offline may solve this problem, but i prefer online all the time)