Well I don't know, but have some vague ideas........ if you leave it somewhere dry, the wax will eventually flake out, you may not have time for that though, otherwise a solvent of some sort, but then you'd end up with solvent/wax mix but that then may be soapy water washable. I'm sure now we all understand what you mean someone will come up with a brighter idea.
It might be awkward with that shape of jug but on a parallel sided one with a wide neck I used a hot air paint stripper, then using oven gloves to hold the jug ram in a bundle of paper towels and rotate. If the jug is hot enough then this will remove virtually all the wax.
Any residual wax left over can be removed with some caustic soda (sodium hydroxide) in a water solution, or with a spray on oven cleaner
Back in the dark ages, I used to clean the worst of the wax from my (metal) candle moulds by putting them upside down on a tray in the oven. And turning the oven on to a very low heat for a pretty short time.
Used to get the worst of the wax out, and the rest was soft enough to be able to remove with kitchen paper.
Had to be very careful, though, with making the oven floor and shelves as wax-proof as possible - Lady DeadDiplomat could be a fearsome sight otherwise!