In first place, BTC are not stored anywhere. What is stored in a wallet (file) and thus in a hard drive is the private-keys which allows someone sign and validate the transference of BTC from one public-key to another public-key. In other words, the only thing stored in a hard drive is a pre-defined password which allows any user to send BTC to whatever Bitcoin address they want. With that in mind, I stated that there is not a system embed in the Bitcoin protocol which allows an user to delete the BTC already supplied. Anyone can just delete a private key in their possession, but no one can command the protocol to delete the BTC supplied.