EFI variable storage full

I rebooted my tablet because of a wireless bug that occationally crops up, and the UEFI couldn’t find any operating systems. I’m in the process of relocating, so I don’t have any other computers here. Not to mention no USB keyboard. Luckly, I remembered that I had a Debian install image on a thumb drive, and luckly it was in my backpack. So, boot it up and get into graphical rescue mode (no keyboard!