Remove website from google to start again

So i was silly. I bought a decent expired domain and used the rent a serp theme on it to target different cities. Long story short, rent a serp is a pile of shit and i basically wanna remove everything, deindex everything and use the domain to build a new site. From what i am reading this is not a straight forward thing. Hoping someone has experience of doing this and can tell me the best way to go about it. The domain has good metrics so i dont wanna lose it. Just get rid of everything i have done since i bought it and turn it into an affiliate site

Just put what you do want on the Website and google will reindex everything and obviously the old stuff will just disappear. You might be able to speed things up a bit by setting up Google Webmaster tools and submitting a sitemap etc.

Honestly that easy?. I thought there was more to it?