An article on painting cabinets
https://www.familyhandyman.com/kitchen/diy-kitchen-cabinets/surprising-tips-for-painting-kitchen-cabinets?pmcode=IVBJJU103&_cmp=DiyTipsHints&_ebid=DiyTipsHints7/2/2017&_mid=155448&ehid=EBC4D8BEC6F08D97A318788DB78D9A1244AF138A
HINT: if your cabinets have Euro-hinges, most models will separate the door part from the frame part and then you can unscrew each separately. (In fact, if you order these from a commercial supplier, you have to order the hinge (cup part) and frame mount separately)
And a video (interesting enough, this guy called me with a half-stripped nightstand and I ended up refinishing the nightstand and bed for his daughter.
And, Kevin, there's likely no probability that a factory finish is "polyurethane." Not all clear finishes are poly!