Do I still need my iTunes library stored on my mac hardrive now I have apple music?

My iTunes library is about 33GB. I've been using Apple Music for a while across Mac/iPhone/iPad, and happy with it. I am finally willing to let go of my iTunes library (or more specifically, archive it on an external hard drive *just in case*).

To use Apple Music on my Mac, and avoid issues with other devices linked with the same Apple ID, do I need to keep all the music downloaded on my Mac?

I'm thinking along the lines of the "optimise storage" option on iPhone, to limit the amount of music that is downloaded locally.

Thanks