Create Local Admin Group with no connection to Domain

We're working on a remote workstation which has been set up especially for us to install our software on a trial basis. No other users and no other (non default) software.

They've set us up as a standard user which is useless. We need full admin rights. They're reluctant because (I'm assuming) they've added the machine to their domain and all members of their administrators group have access to their corporate email system. That's reasonable enough but it strikes me, as a non windows policy expert that they are missing several possible alternatives.

1 Set up an admin user in a standalone admin group (which has local admin rights only - no connection to the domain)

2 Exclude the machine from the domain

3 Create a standard user with enhanced priveleges (equivalent to admin)

I tried to google how to perform option 1 and found it easy enough to create a new group but impossible to find instructions on how to set the permissions for that group other than on an object by object basis which is clearly inappropriate.

I'm sure (2) can be done but I know nothing about how

I suspect (3) is also possible but, again, I don't know where to begin

And I wouldn't be surprised if the experts hereabout will come up with a dozen more options.

The simplest is the one I'm after!