@nohillside Things got slightly better in beta 7, but the issue is still not resolved. :\

Good thinking, except this "removes" the Mojave background in the Desktop Background preference pane.

Also, try using verbose mode and taking a video of the boot. Hold Command-V while turning it on until the screen turns on with white text. Take a video until it fails, then review the footage and take screenshots of the messages immediately leading the KP. Edit your question with those.

Try clearing your NVRAM. Hold Command-Opton-P-R and turn on your Mac while doing so. If that doesn't help, try safe mode. Hold Shift while booting.

Try doing it online at appleid.apple.com or on your phone

You can remove an icon by holding Command and dragging it off the bar.

Actually, macOS Mojave is being seeded as a public beta as well, and I think it is available right now. beta.apple.com

Enabling the root user on a Mac can open major security holes, especially for end users. If you need to use the root user by command line, I recommend using an administrator user, typing sudo su to switch to root. It will ask for a password.

Nice Ubuntu font.