I suggest avoiding anything illegal.. like illegally dumping it in a garbage bin outside the back of some store... Most places now have camera setup to catch anyone illegally dumping into patron garbage bins... I'd avoid that if i were you cause the last thing you want is to be caught red handed with bags of soil.

In all honesty it's not a huge problem.. If you have a balcony or a back porch simply bag the soil up in a black garbage bag and put it outside.. Like Stinky says, come spring time... break it up and use it in your yard.

Keep it away from your plants though as dead material is a feeding ground for pests... that's why i say outside.

Cheers,
bob.