Changing AD bind password

Good morning,

I recently changed the password for the AD bind account that gitlab uses to search our AD for credentials, and for some reason I cant log in with what I thought was my local admin credentials.
Whats the best way to either 1: reset local admin creds, or 2: change the AD bind password in terminal config?

I have tried the instruction document for resetting the root password, but the user.where returns => nil and user.find_by returns NoMethodError: undefined method `find_by’ for nil:NilClass