Warm wax is like golden syrup, it's pretty stiff and thick when cold but it will move.
Wear disposable gloves, put a smidge of oil on your gloved fingers, then stand the heater on several sheets of couch roll or kitchen paper. As long as there's no wax around the electrical socket, plug it in and switch it on to around 60° (or 3 O'clock if it's not digital)
Use spatulas and scrape off as much wax as you can. Clean up with wax equipment cleaner. If you don't have any you need surgical spirit and a little smidge of oil on your cotton pad. Be careful as oil will make everything slippery - so don't go mad.
Remove the wax pot insert when hot. Hold it gingerly with a wax strip. Clean the outside of the wax pot with surgical spirit on cotton wool being mindful that there is a risk that the vapour will ignite. So keep the bottle lid on and away from where you are working. Use cotton wool to soak up the warmed wax and discard. Use surgical spirit. When the wax pot is clean, set down on a couple of wax strips.
Now drop a handful of cotton wool into the wax pot hole and stir with a spatula to soak up warm wax. Clean up with surgical spirit as before.
Don't use white spirit on plastic equipment and definitely don't use white spirit on hot equipment. It's excellent on cold, non plastic things like the floor.