You can't have too many high-quality posts on a blog. Your oldest posts get very little traffic, however, even fewer 2 people visit the page each year, it is still traffic. That person may see a related post on the page that interests them. If you don't have a plugin for showing related post, get one. It may help keep your visitor on your blog. Deleting pages with backlinks is counterproductive to SEO. You can delete old posts if you redirect visitors to related posts with fresh, relevant information, You don’t want visitors to receive 404 errors when coming from a search engine or an internal link on your site. If your posts are old, thin content that don't have internal or external links pointing to them, you can delete them. Google uses quality content as a ranking factor, and if your posts are from a period when quality content didn't matter as much as it does today, you can delete them. After the Panda update, Google ranked websites based on the overall quality of a website, whereas before, Google would rank individual pages based on their quality. You can update the posts you want to save with additional content and tagged images, but make sure you get around to it quickly. Post your updated posts on social media as you go, which gives you much needed social media content. Don’t be afraid to delete articles with 500 works or fewer that have no links pointing to them, especially if the content isn’t relevant anymore. Turn over a new leaf and create long, well-researched posts with images or video. Include one or more internal links in your post to provide readers with additional information. Finally, you have one more option; tell Google not to crawl older posts and leave them alone. For more information click here https://www.reddit.com/r/SEO/comments/a6wkoe/shouldideletethepagesonmyblogthat_have/.