Useless articles in bought domain!!

[bsystems]

Recently I bought a domain which is in .de, the domain has many articles published in it which gets some good amount of traffic. Lets say that if I use adsense then it shall make $50 per week. Now most of the articles are useless and garbage content. For the niche's sake those useless articles are needed. It will be like writing a book on SEO but not talking about link building or on-page optimization. I hope you guys get my point here. So, what should I do? Those articles numbers are in tons and they create a huge database drag.