Hmmm. You could try gingerly prising it out with a screwdriver all around it.
Maybe find a wheel of the same type you are willing to sacrifice and experiment on that first.
The problem with screwdrivers for this job is that they tend to have a few sharp edges, which can cut the tyre and damage the hub.
I've had success in the past by using 250mm motorcycle tyre levers, or for the thinner tyres, pushbike tyre levers would be the go. I guess car tyre levers would work as well, if used with care.
But yes, the hot/boiling water pretreat is the go, for sure.
