Options to follow the rules and not have the aggravation (and stress) of constantly fighting the system... cheapest to most expensive.
1) Pay the extra to have the people delivering the new mattress to take away the old, which requires you to not be fighting the system on delivery (who/how) and where you acquired the new bed/mattress... Most delivery services working with legit retailers will offer this option, furniture, appliances etc. Used stuff go to option 2...
2) Rent a uhaul (or friends truck) and take it to a transfer station, combine with other people in the building, friends, combine a pile of junk and/or use the van to get new stuff like Ikea or a new motorcycle... (to lower rental cost impact). if it is a city transfer station they may not (last time I used a city one they did not) charge under a certain weight. If it is private one you always pay but cash goes a long way price wise at these. Private ones have better hours. Many times there is a uhaul near the transfer station as well...
3) Call any of the 1-800 guys that take away junk, again pay for the convenience.
In your other thread about the meaning of life...sometimes just flowing with the system reduces stress and therefore results in an overall happier life. Sure it (may) cost a few $s more but why stress about it. Fighting the system, well that just adds stress and is it worth it in this case??? Your problem in this case has been completely solved, you just pay a little for the solution.
I know all this well, lived in a condo for a long time, still do some of the above at my house... in the end fighting the system may also be more expensive time and $$$s wise.