The Disabled command inserts a Disabled component at the cursor location (screenshot below). (To put the Disabled component around selected content, use the Enclose With | Disabled command.)
Content inside a Disabled component is ignored in the output. So you can add content that you want to ignore to the Disabled component. The Disabled component thus serves as a way to comment out content.
When you want to reinstate disabled content, simply remove the Disabled tags from around the content. To do this, select the Disabled component, right-click, and select Remove Tag Only.