OTRS is a great software it’s not 100% documentated. I find this tip digging the source code.
Imagine that you want to remove the Priority link from Nav Bar of Level 1 Agente Front end, while he/she is viewing a ticket and you want it to be viewable only for supervisors.
Go to ADMIN-> SysConfig -> Ticket -> Frontend::Agent::Ticket::MenuModule
Then find the parameter you want to hide/remove. In this case, Ticket::Frontend::MenuModule###300-Priority
Add a key called “Group” and the put “rw:group_that_has_access” as the content. To add more groups, separete with “;”. For example: “rw:admin;rw;supervisors”.