CLion displays the Welcome screen when no project is opened. For example, when you run CLion for the first time, or when you close the only open instance of a project. From this screen, you can create a new project, open, or check out an existing project from version control.
If you have previously opened projects in CLion, you will see a list of them in the right-hand pane. You can start typing to find a project, click to open it, or remove any project from the list using the context menu or the screw nut icon.