inserted a SD card and records as advertised. Can the recordings be deleted from within the app or do I have to remove the card and delete data through my PC?
The ability to format the card from the app (which would delete the recordings) is currently in beta. You can wait for the beta to become the published version, or you could join the beta testing (see the beta section of the forum).
BTW, when I say that formatting will delete the recordings, I mean that they will no longer show in the app or in the SD card’s directory. However, the actual content will still be on the card until overwritten and could conceivably be recovered with advanced tools. In order to securely delete the content, you would need to remove the card from the camera and accomplish the secure delete on a computer.