When you add a CD to the database using "Scan CD-ROM" feature, OrangeCD should already set the exact number of tracks. You cannot add or delete tracks from the CD entry.

If you want to be able to change the number of tracks, you need to create a new database entry using "Add manually" or "Duplicate" menu commands. In this case, Tracks page of the dialog has small buttons on top that can be used to add or delete tracks.