iphone on apple account???

Setup my new mac mini today i was well overdue to upgrade my 2009 imac getting used to the new settings i dislike how they mimic ios. Anyways during setup i entered my apple id info and then it asked me to enter the pin number from my iphone which is wierd cause i have a "work" iphone but not a personal iphone anyways i entered that pin number and it worked. So somehow my work iphone is tied to my personal apple id? How do i get it off? In the iphone settings it has its own apple id through a work email not my personal email so im not sure how it even got attached in the first place