it is impossible to do that unless you start the game over again and don't collect the item you don't want
To remove key items in Pokémon Emerald using cheats, you can use a GameShark code. One common code is "BFF956FA 2F9EC50D," which allows you to remove key items from your inventory. Activate the cheat, and then access your bag; the key items should be removed. Remember to disable the cheat after use to avoid unintended effects.
You can unregister them but you can't remove them from your pack
Key items are impossible to trade or remove, except to Pokémon Colosseum.
Unduplicatable ItemsThe only Items you can't duplicate in Emerald are Mails, because you can't store a Pokemon holding Mail into a PC. You can't clone any Key Items either.
To get to new mauville
To remove key items in Pokémon Emerald using cheats, you can use a GameShark code. One common code is "BFF956FA 2F9EC50D," which allows you to remove key items from your inventory. Activate the cheat, and then access your bag; the key items should be removed. Remember to disable the cheat after use to avoid unintended effects.
As far as I know there is no code for key items.
Ruby & Sapphire Key
You can unregister them but you can't remove them from your pack
Key items are impossible to trade or remove, except to Pokémon Colosseum.
Unduplicatable ItemsThe only Items you can't duplicate in Emerald are Mails, because you can't store a Pokemon holding Mail into a PC. You can't clone any Key Items either.
you can't
When facing water, open your bag and go to key items. There select the Super Rod and then use it.
There is no key it opens when you become a Pokemon champion.
select
you can't delet key items in any Pokemon games.
where you use the key to turn on the quary.