Accidentally pushed erase - now computer is locked
I made a very dumb mistake and accidentally started an erase on my son's iMac through find my devices on iCloud. The Mac used to be mine and I just wanted to remove it from my iCloud account so he wouldn't be getting my messages, but mistakenly started an erase. It has been a good 18 hours and the erase continues -- all he sees is a black screen with a progress bar. What should I do to get him back on there? How long will it take?
iMac 24″, macOS 12.0