Comment Out is a very simple WordPress plug-in developed to allow users to keep text in posts but not display it on the live page. I mainly built this plugin as a way to try out Wordpress Plugin development as well as get into hobby/side project programming.
It uses shortcodes to designate which text should be hidden to viewers. The plugin also provides a page that lists all the current comments you have across your site. This can be used to keep track of where you have commented and remove the comments when you are ready.
You can go here to download the code or install it on your WordPress site.