How can I clean everything out?

I don’t need all my present files anymore, and I’ll build a whole new website, so i want to clean everything in my hosting plan(files/databases and other evidences showing that I’d have a website before), but how shall i do this? is there some “one-click cleaning”?

Not a complete cleaning, but go through Domains, Users, Email, and Databases and it shouldn’t be too tough to pick the pieces out.