Rekordbox & iTunes, how to get rid of iTunes?

Hello, I hope that you are able to point me in the right direction.

I am using RB V5.8.5 on a Macbook Pro, High Sierra 10.13.6. Quite some years ago I started to use RB with iTunes. After downloading tracks, I move them from download folder -> iTunes -> then delete the tracks in the original download folder -> then I copy them from iTunes to RB and leave the original tracks in the iTunes library. RB then has a shortcut to that location. In RB I created tags/cues.

I agree, this does not make sense at all LOL. 

1- I want to get rid of the inefficient iTunes work flow. iTunes is not needed. I assume that I need to migrate the music stored in the iTunes library to the external HD. Then relocate the tracks in RB. But how?

2- I only have a 250gb internal HD and it reached it's max. App 150gb of music is on there. So I need to restore my music on a external HD.

Any help is welcome. Thank you.