Is there a way to access/explore (and more importantly, manipulate) WP8 system files either from a computer (Windows, Mac OSX, or preferably Linux) or from the phone itself? What I am trying to achieve is access Whatsapp's auto backups and delete them. So, if there is a way to get around that without having to access the system file, please share your knowledge.
There is currently no way to access the general file system of a Windows Phone 8 device, especially the storage used for each individual app.
The only access you have is to the Documents, Music, Video, Ringtones and Pictures when your phone is plugged into a PC.
In the case of WhatsApp, you should contact the developers and ask for a feature to clear out old backups or export them.
There is no way to access the system files on Windows Phone. Also, whatsapp has no backup files (Not on the phone nor on it's servers). If you want to delete all your messaging data from the phone you have to reinstall whatsapp.
try the steps are in this youtube link, just copy paste system path using winRAR, when phone is connected to a windows pc -> https://www.youtube.com/watch?v=j03Q6yEi6K0