Please attempt to follow the guide to become familiar with the Wowza documentation. Here are the steps to get you going:
1) In Streaming Engine Manager, click the Server tab and then click Users in the contents pane.
2) On the Users page, click the Edit icon of the user name for the administrator account.
3) Confirm the user access level is "Administrator"
4) Select the Allow access to advanced properties and features check box. And click save.
Note In the past I had to edit my admin.password file before I was able to make these changes. If that is the case for you as well do this.
Edit [install-dir]/conf/admin.password and add a group|group entry:
# Admin password file (format [username][space][password][space][group]|[group])
#username password group|group
user pass admin|advUser