Remove uploaded music from library whilst keeping Apple Music adds

I’m looking to remove all the personal music I have uploaded to my iTunes Media library whilst retaining everything I have added via Apple Music. 

I have quite a large collection of mp3s (over 800GB) that I want to remove so I can re-sort locally first then start again. I don’t want to delete all as I have also added quite a lot to my library through Apple Music, anyone have any ideas of the best way to do this?