Surprised no one really gave you a good solution until now..
press F5 and type in the console: devcommands
After you enabled it, type "removedrops" and it will remove all the dropped items within a certain range

Items dropped out of range of workbenches eventually decay and despawn in my game, always.

Time to move my trash hole then.

I build a house with a pit inside, and the removed the workbenchs around it.
Thats the trashbin house and things despawn in the hole, not fast but they do.

Spoiler below:
Or make a platform over the edge of the world with a portal. All it takes is a quick YEET from there.

I do see items despawning when i throw them in water sometimes, but most of the time they are still there even days after. What i end up doing sometimes is creating chests to tuck them away from my base like nuclear waste.

Surprised no one really gave you a good solution until now..
press F5 and type in the console: devcommands
After you enabled it, type "removedrops" and it will remove all the dropped items within a certain range

Originally posted by are you a part of the 99%?:

Surprised no one really gave you a good solution until now..
press F5 and type in the console: devcommands
After you enabled it, type "removedrops" and it will remove all the dropped items within a certain range

Pretty much the only reasons i have console commands activated :P

Originally posted by are you a part of the 99%?:

Surprised no one really gave you a good solution until now..
press F5 and type in the console: devcommands
After you enabled it, type "removedrops" and it will remove all the dropped items within a certain range

If you go this way, a more convenient solution can be found here:
https://www.nexusmods.com/valheim/mods/441

Not yet really beyond dumping stuff off a so into the ocean where it will sink.

Going for a "delete item" function soon. Been asked about enough that it should get a look.

Only outside workbench range.

Yes, leave them outside a player base area (over 20m away from stuff you've built) and they despawn within 2-3 game days. Drop them into 2m+ deep water to despawn them within a few minutes.