There are 2 main types of CDs: CD-Rs and CD-RWs.
* If the CD is a CD-RW (or CD+RW) then yes, you can wipe it and start again. To do this use any CD burning program: something like Nero would do fine. * CD-Rs are not erasable. However, if you originally created the disc with something like Nero, you may have been offered the option of "Starting a Multi-session disc" or something like that. If you chose that option, then you would be able to burn more files onto the CD until it is full, however you still would not be able to change or delete existing files.