No one has mentioned a no-cutting removal technique for Bp/W single-piece harnesses, so I will.
At the surface after getting victim buoyant, face up, & waist unbuckled
1) Lift both victim's arms so they lay pointed straight "above" their head
2) Now position yourself to the side of the victim.
3) Rescuer's hand farthest from victim's head goes under victims mid-back
4) Rescuer's hand closest to victim's head pushes down on backplate
5) Lift victim, push down on Backplate and spread your arms apart.
6) Victim slides out of Backplate
BC should be less than fully inflated so you can gently sink it, but still inflated enough that you're not treading water to float both it and victim. If that's too complicated think of this analogy:
Your toddler spilled spaghetti on his shirt. When you pull the shirt off your toddler where do their arms go? Up and over their head.
Put your victim's arms like that and you can slide the Bp/W off easily without cutting.