If you leave items out in the world away from the control area of a workbench they'll go away. Go throw your garbage in the ocean for realism.

It would be nice to get an official non-mod trash slot for the inventory, yes. For now, like the guy above said, just toss it on the ground outside your workbench area and it will disappear after a couple in-game day cycles.

create a new world, drop off items there, delete it occasionally

also works for traveling long distances with heavy/non portable items

I wish I could sell items that are possible to produce.
If you couldn't sell production items, it would be nice to be able to easily delete or recycle any item.

Can also make an Equipment Wing for your museum. Display all that old stuff along with the heads of your enemies!

Throw them outside workbench radius, they despawn within a few days. Throw them into water 2m or deeper they respawn much quicker.
The current method stops people from complaining because they fat fingered something and deleted it, which happens in any game that gives you a trashcan/delete option.