If you close it, you'll need to enter your password yet again to make administrator level changes. (howtogeek.com)
The User Account Control basically notifies you before changes are made to your PC — not all changes, but only those which require Administrator level permissions. (thewindowsclub.com)
There are several apprenticeships available at administrator level; see the government apprenticeship website for vacancies. (targetjobs.co.uk)