Can't delete a admin user on MBP with High Sierra
I created a new admin user as part of a trouble shooting session, I'm now running out of space and things have slowed down. I went to System Preferences - Users & Groups and tried to delete the extra user, but the "-" is grayed. What should I do other than brute force delete the user files (which will leave I'm sure some hidden stuff). I'm on a 13" 2016 Mac Book Pro with a 250 GB SSD (thus the issue of space).
Macbook (2016 or later)