I’m no longer using My Book Live Due as a Time Machine to backup my iMac, I’ve already stopped using it from the console. If I don’t need the old Time Machine files stored on My Book Live Due, can I just simply delete them manually?
You need to map the drive with the information provided in the link but instead of using SMB you would use AFP and you will be able to access the time machine share and delete the files there.
If you have SSH enabled, you can use a SSH client like Filezilla to connect to the MBLD and browse to /shares/ where you will see the items you are interested in. You can delete them using the SSH client.