Watchdog may tell you to read the instruction manual. Quote from page GB 50 of my version.
5. Select Format and press the OK button to remove all the
recorded programmes saved on the HDD and initialise the
HDD.
6. Select Yes when the format confirmation message appears and
enter a password to start formatting the HDD.
Note:
• The format deletes all the recorded programmes saved on the
HDD including TV, radio, MP3s and photos. Formatting does not
delete the system files of the product.
If you want help on this or any other forum then I think you are going about it the wrong way.