large candle in glas cylinder

[Sonilaa]

I was given one of these large candles which fills an entire large glas cylinder with about 20 cm diameter. the candle has burnt down now, but there still is about half of the wax left.
how do I get it out so I can use the container for flowers or tea lights?
smaller ones I would put in the oven on top of kitchen roll at a low temerature to melt the wax, but this is a huge amount, maybe more than a litre.

hack at it with a knife to expose the wick and burn the rest. or if the wick is unsalvageable just hack at it till its all gone then put boiling water into get rid of last bits

the wick ended about half way through the wax, but most of the wax is on the sides + a big lump of wax on the bottom of the container... maybe I will try the oven and hope that the wax doesn*t flood the oven...

Putting it in the freezer might be safer, I do that with wax tarts in my tart warmer and they pop out once they're frozen.