Have you tried accessing your SD card on your PC, only to see it is full?

First things first: the BlackVue utilises Loop-Recording. This means the oldest video file is going to be overwritten by the newest one, when your camera is recording.

Therefore you do not need to be worried when your card is "full". 

If you want to format your SD card, you can do so under the steps here.

If you are trying to remove footage from your SD card, and it is not letting your or granting you a "permission error", then your SD card could potentially be corrupt. Please get in contact via a ticket or the live chat to see how we can help you further.