Be careful! Some states will not allow you to collect unemployment if you resign. No matter if UHC says they'll not contest the unemployment claim. If you voluntarily leave, then it's a wrap with some states - flat out denial. Please weigh these choices carefully.
If you're on the cusp of retirement, then sure. If you can financially, sure - do what's right for you. But if you're not anywhere near that age, I highly advise against volunteering for this. Put your hand down, and let them let you go. As some one who was let go in a blue state (as I've seen some say on this site) you can get unemployment. Document everything, show proof of what they're doing and that they gave you a choice, and for God's sake consult an attorney!