I used to do Air drop and bounty. Get all coins in time when the market is down. The value of all these coins lost 90% even now looking at it I do not believe it is no longer valid.
I cannot sell them because no one buys them, and its value can only be enough to transfer to exchange.
So do you have a way to hide it or delete all the coins from your wallet?
No, there is no such possibility. In your case, it is easier to create a new Ether wallet.