You cannot sell any kind of magic items. There is no way to convert a magic item into gold.

Permanent Items

You cannot sell permanent magic items.

You can trade permanent magic items according to the rules in the ALPG. See Trading Magic Items for more information.

Or you just keep them in your character’s “vault”.

Consumable Items

You cannot sell consumable items.

You cannot trade consumable items.

If you cannot use a consumable item yourself, bring it to a game and allow another character to use it. If it goes unused, it returns home with you though.

Or you can just add it to the pile in your character’s “vault”.