How to unregister from Signal if you no longer use it as your texting app

Recently I encountered an issue while trying to text a colleague who no longer uses Signal. This app is popular for its range of features including encryption, wifi-enabled texting and encrypted phone calls. So it didn’t surprise to me to learn that they were a user. But they were a lapsed user, and this was the source of the problem.

Folks who have started using Signal and then stopped might find that their not getting all of their texts.

The reason is that even if a user uninstalls Signal from their phone, the Signal infrastructure doesn’t necessarily understand that the user has done so. So the texts from other Signal users that are intended to arrive on this user’s phone, simply don’t. I guess maybe they just end up on the Signal server or something.

Anyway, there’s a solution: unregister.¹