I had the same problem. I was running out of space.
Deleting old device simulators did NOT help.
My space issue was caused by xCode. It kept a copy of every iOS version on my macOS since I had installed xCode.
Delete the iOS version you don't want and free up disk space. I saved 50GB+ of space.
NOTE -> can't you see ~/Library inside Finder? It is hidden by default. Use Terminal and type cd ~/Library/Developer/Xcode/iOS\ DeviceSupport/ or google how to see hidden folders.
NOTE -> if you have multiple users on a single macOS machine, make sure to find the directory ONLY with the user account that originally installed xCode.