Which recordings are you referring to ?
Recordings on a USB storage device or videos that are on the T3's hard drive ?
The ones on USB device can be deleted by attaching device to a Laptop and open the contents and delete as needed.
If you have recordings/videos on the T3 drive itself, then on Home page...
Settings > Storage & Reset > Internal Shared Storage > then select the option wanted (photos and videos for example) and open it and see what options are there.
If that does not work as you would like, then there are File Managers that can clean content from Internal Storage.
I think it was the 'FX File Explorer' that I saw had that option, but it could be some other one, perhaps maybe Total Commander..
http://iptvtalk.net/forumdisplay.php?208-Tools