Forgot to give admin rights to an account in Win 11

Hello,

Typically I create install or admin local accounts for a local windows PC so the user doesn't accidentally install a virus with admin rights.    I rebooted before I assigned admin rights to the install account and the default user doesn't have admin rights.   This usually a big deal as I'd just hack the windows set up -  however this is a dell PC and if you boot off a thumb drive it doesn't give you access to the default formatted raid drive.

I tried to follow this - however with Windows 11, you don't get startup settings under troubleshooting - you do get startup repair which won't help.   If I try to run msconfig in windows - that requires admin rights.

I could just reformat but I'm curious if there is another solution to the problem.