If I was to decide whether delete every altcoin or leave the situation as it is, I would keep all the altcoins. Because they are the history or knowledge. They demonstrate how people can be naive and believe in lies, how people invest in things that will never make them rich or will opposite - make them rich easily. Altcoins show how different can be cryptocurrency world.
Some would like to delete it would be people who had invested in wrong coins or ta wrong time and had taken a loss due to which would like to forget that as an nightmare. I hope when the prices are falling people do invest in such times and not at high as this will help them make money when it rises.