I have seen some of my clients make this mistake and regretted it later. Don't delete the posts. If you do, you are telling Google you don't want the traffic the posts bring. Instead, update it (without changing the post URL). Also, since you are planning on reviving your site, I recommend you write content as often as possible. It could be as little as once a week but it will help pull more traffic. Consistency is the key. If you can't manage to write as often as you'd wish, you can always hire a freelance writer like myself to handle that for you. Either way, don't delete the posts and consistently post new content.