Hi there! Sadly you cannot change a page type. What you'll want to do is create a new homepage, using a blank basic page type. Then in the page you have already designed, save each section to your favourites, click the heart symbol in the pop-up section settings:
Then go to your new homepage, and add sections, picking from your favourites.
Then in the page settings, set your new page as the homepage, finally delete the blog homepage.
Hope that all makes sense!