Depending on what kind of pickup you have, there are several things I do. For single coils that have black or gray Vulcanized Fibre for the flatwork (the material that looks like compressed paper) you can use a heating lamp or low temperature oven to slowly melt the excess wax.

If you use hot water to melt the wax, too much moisture can be trapped inside the bobbin and causes the flatwork to warp and magnets to rust. If rusting occurs it can eventually break through the insulation, damaging the coil. Make sure the coil is dry and moisture free.

When removing wax from humbuckers, I disassemble the hardware such as the magnets, iron load, shims coil forms (bobbins) and bottom plate. When removing wax from each component, I have used hot water, heating lamp or a low heat oven. (do not use a gas oven because the wax is extremely combustible) If the parts are submerged in hot water, I carefully dry each part using paper towels and even a hair dryer. You can use a small bowl to put hot water in and let the parts sit for a while. As the wax melts of the parts, it floats to the surface. I put a paper towel on top of the water to absorb the excess floating wax. This helps when removing the parts so they don’t become coated with wax when pulling them out of the hot water. I wrap a thin wire around each part to allow me to agitate the part and not burn my fingers with hot water when taking the parts out of the container.

A heating lamp works well too, but be careful when using plastic bobbins (coil forms) because they can warp and distort if they get too hot. Pickups can be re-dipped in a paraffin (wax) solution to heat and eliminate excess wax. I have used an Electric Heat Gun that delivers an instant flameless heat. Some have an adjustable air intake that allows you to vary the velocity. Again be careful on plastic parts as Electric Heat Guns can melt or distort the plastic.