Editing/Copying DVD and CD

I used the program k3b for creating DVDs.

Erasing DVDs when the option for erasing DVDs in k3b does not work, we can use the following syntax at the terminal $\framebox{ \texttt{ \textcolor{red}{\bf sudo dvd+rw-format -force /dev/dvd} } }$ or also
$\framebox{ \texttt{ \textcolor{red}{\bf sudo dvd+rw-format -blank /dev/dvd} } }$ . The later did not work for me once.