In Viber there is a community chat option where one member is a super admin who deals with the chat.
If someone creates issues and uses abusing words in chats and creates violence. So admin need to stop them and block the user.
That's why there is a need to delete messages. Don't you worry about it because Viber has a solution for this as well.
If a super admin needs to delete any message in the chat of any other member.
Long tap the message then select delete from the options and click on confirm button.
This way the message will be deleted and the problem will be resolved. It is super easy to delete any message for super admin.