If you want to select which Main method gets run, you can select that in Project -> Properties under Startup Object. There are various requirements that need to be met (like being static) and you can only select one at a time.
If you want to call the main method on multiple static classes, you’ll need to create a main one that calls the other ones. You could get complicated and use reflection to search your project for the classes, but it’s much more work than just statically calling them.