How do I clean up iTunes Library and Apple Music confusion on MacBook Pro?

I created iTunes Library around 15 years ago. Some how my iTunes library, albums, songs and playlists have drifted into Apple Music, but with duplications, compilations and confusion.

I’ve found on my MacBook Pro, iTunes Library with .itl files, a library.xml file and my playlist is saved as MEPG-4 audio. 

I want to clean this up but not sure what the best way to approach this issue.

Bob

[Re-Titled by Moderator]

Original Title: Apple Music Questions