You don't want to share the username and password to your master Brewery Account, but you want other Untappd users to be able to manage your beers with their personal account. Never fear, it's a easy process!
After logging in with your brewery account - hover of your profile icon on the top right of the page, next to the search box, and select Brewery Settings. Then select Managers and you will be greeted with this page:
You can simply start typing the username of the person you want to add on Untappd and their name will show up below.
Once you select them, they will automatically get an email. The next time they view your brewery page, they will see this banner on the top of the page:
If the user is not on Untappd, you can invite them to join by clicking on the "Invite User". The user will receive an email and upon joining Untappd will automatically be added as a Manager.
If you have any other questions - let us know at http://untpd.it/newticket.