Avoid manually adjusting the project files unless it’s necessary. You can simply migrate your assets & blueprint by right clicking on them, navigating to the Asset Actions section on the menu that pops up, and choose the Migrate option which should appear once you hover on that section. You can also choose a folder as a whole and the Migrate option won’t be hidden under any additional menus in that case. Then you can choose your new blank project as their new home 
Also, you can always create a new player controller blueprint either in your current project or in the new project that you migrate your assets to.