I have Multiple Instances of Three Viruses in Backup Files

I just changed antivirus security solutions and virus scans found and quarrentined files from my internal C: hard drive.  I also used Malwarebytes to be extra sure, and I’ve run scans multiple times to I’m pretty sure they are gone.   I have a MyBook 160GB with about 200+  folders of backups (the scan reported 1,824,817 files checked).  Some where along the line I had windows backup zip all folders to get more storage.  So now I have a virus report of 51 virus instances in zipped folders, making them hard to dig out.  Scans report that there are three viruses replicated in 17 backups = 51 instances

My question is?

Is it better to delete all files or what are the consequences of doing a full reformat of the drive.   I really don’t want to quarantine these files on my internal HD.  I don’t need the current data on the drive as long as I can wipe it and successfully run new backups.

Hello, if you don’t need the files you can just delete the hard drive and start a new backup.