Znuny Open Source Ticketsystem

This would be for the agent interface. I want the users of the system in my organization to treat every incoming request as a phone request only and not send any outgoing emails to customers.

I was wondering if it is possible to edit the OTRS toolbar and disable certain features. I want to disable the option "New email ticket" and edit "New phone ticket" to just read "New ticket" instead. How can I go about to do this?

I use OTRS version 3.0.3.

Thank you.