Wowza by default is installed using root privileges and runs as the root user. If you are logged in as a non-root user you can prefix the command with sudo, and it will prompt you for your password.
Note that you can perform an advanced configuration of Wowza to run the service as a named user.
The link I posted in my previous reply demonstrates a framework for running Wowza as a non-root user. This needs to be carried out by hand after installation. The current default installation and execution on Linux/Unix operating systems is all carried out as the root user.