Don't ever do this on a current bare metal system!
Even if you have everything backed up, plan on re-installing anyway, and just want to see what happens.
On a modern EFI system, recursively deleting everything (including the EFI path) has a chance of permanently hard-bricking your computer! https://github.com/systemd/systemd/issues/2402
In a properly implemented EFI, this should be possible. But there have been cases with improperly implemented EFI in some laptops/motherboards where the computer won't POST after /sys/firmware/efi/efivars/ was nuked. In that case, accessing BIOS or booting from a flashdrive isn't possible anymore.