If you need to adjust the number of modules in your course site, there are two ways to add and delete them.
You can click on Edit settings in the Course administration block to increase the number of modules to a set number. Open the Course format options area. Update the number of modules to reflect your needs. Scroll down and save your changes.
To add or remove modules one at a time, turn editing on. Scroll to the bottom of your course home page and click on the plus sign ("Increase the number of sections") or minus sign ("Reduce the number of sections").