Are they the black plastic fittings with the two white taps to push in? No need for heat, you need to push the hose towards the core/component slightly, and then press in on the tabs under the fitting, NOT the shit sticking out the end of the fitting. It's not super easy, but it will work. The OTC removal tools are kind of a joke, you don't need them.

And don't reuse the two rubber and one plastic O rings going back on either.