Open file playback in camera, unlock and delete In PC you delete locked files immediately.
The remote control button is only used to lock the currently being recorded file.
Simply format the card inside the camera. It will erase everything. If you use a computer to remove/erase files, then you should be formatting the card in the camera before using it again anyway.
Would be glad if Viofo can make the app able to delete the locked file. Doesn't make much sense if it can be deleted on camera but not via app. App is also more convenience.
Locked file is normally what you like to see first so sometimes you just like to download the locked file via app to your phone and delete it without deleting the entire SD card as you're worried that you may need to go back and use some of them a bit later.