How do I make Bitcoins disappear?
You can't destroy them like you can with paper money. Just moving them between wallets, paying fees or giving them away doesn't really disappear them, they just move around in their place in the blockchain.
You can put them 'out of reach', by destroying all records of the private key, but they still 'exist'.
^^ possible to make them unreachable, take out the HDD and destroy it, but do "exist" as (s)he says^^