A blog page is just like any other page on your Portfoliobox website. Unpublishing your blog allows you to work on it as a draft before publishing it. This means that your blog page exists but is not visible or accessible to your visitors. When you are logged in as Admin you can always view and edit your unpublished blog. If your blog is your start page make sure that you choose a new start page before unpublishing it.
To publish or unpublish your blog page:
Click on Manage Pages in the top-left corner.
Select Edit existing pages.
Hover over your blog page and click on Settings.
Scroll down and click on the Unpublish the Page button.
After that, the button "Unpublish the Page" will be replaced with a "Publish" button, that can be used later to publish the page back on your website.