When you start Irricalc, it automatically creates a project file called Untitled.ic3. The name of the current project file is displayed in the title bar at the top of the application window.
If you open another project or click on the New icon, the program will ask you if you want to save any changes to the existing Untitled.ic3 project even if you have not entered any data.
If you do not want to save the project, simply answer No to continue.