I think I forced my new rims with plastic hub centric rings and now they are stuck, I can't remove the rims off the car.
I have a mustang 07
To deal with this issue I would suggest that you support the car on solid good quality axle stands - or take it to a garage who can put it on a ramp.
Then you need to use a large soft-faced mallet and hit them from the inside ie underneath of the car to knock them off. It is best to hit the tyre not the rim...
I suggest that you do not apply heat as you will melt / deform the plastic.
Kicking them is about as good as good as hitting them with a feather - at least kicking mine did not work, but that was alloys corroded onto the hub. Kicking them may work if you kick them off ie away from the vehicle.