Process for sunsetting a Firefox Add-on

My company has an existing Firefox add-on. For a couple different reasons, we are currently unable to make updates to the add-on. Thus, we are starting to think about sunsetting it. The add-on is currently not available in the store, but we have about 3,000 current users.

If we can’t make updates to it, what is the process for removing access for our 3,000 users? In other words, by removing access to the add-on, the users wouldn’t see the add-on in their Firefox browser, or if they clicked on it, they would see some type of message indicating that the add-on was no longer available.

Looking for any type of guidance on this topic. Thanks in advance.