How to completely remove the backup software & files from My Book External Drive 16 TB

Hello All. I have a 16 TB WD External Drive with backup software. However, the hard drive does not function: When I want to back up my main hard drive onto this, it stops working after a few hours. It starts copying and then when I go to see what has happened the next day, only a fraction (1 TB out of 16 TB) has been copied onto it and the HD is disconnected. I suspect it is because of the backup software as it only happens on this HD. Can someone tell me how to completely remove those backup software & files from the HD, so I can have more space on the HD & hopefully the problem will be solved?
Thanks so much