|Are you talking about disconnecting from a Domain Server that doesn't allow you to install unauthorised software. |
In that case disconnecting wont make any difference because the restriction is in the local machines registry. To change that you need to log on with an Administrators password.
Even if you did manage to make the necessary changes, as soon as you reconnected to the Domain Server, the Domain would reverse the changes and you would be out of a job for hacking the companies computer.