Since the subject of the sentece is "secret chats", it's better to use a third-person plural (they) as it is in English: "Secret chats do not allow forwarding" -> "(Secret chats = Le chat segrete) non permettono di inoltrare".

The phrase which is currently used does not correspond to the subject of the window: secret chats. Therefore, I have added a verb that is linked to the subject and is also forming a more coherent phrase. Moreover, I have included what cannot be forwarded based on the fact that the verb forward in Italian is usually followed by a direct object.

The applied translation is a little too generic. A secret chat is meant to stay secret. This means that it does not allow its content to be forwarded. The idea that forwarding in this kind of chat is not allowed must be explicit.