Finally! Apple has added a small yet incredibly useful feature to the way iOS 9 handles Bluetooth devices.
In the past, you’d have to drop into the Bluetooth settings, tap on an offending Bluetooth device, and tell your iPhone or iPad to Forget the device, just to re-pair it or use the built in speakers. I can’t tell you how much time I’ve spent doing that, especially when I get a call while connected to a speakerphone-capable audio device; I have a lot of Bluetooth speakers.
Now however, Apple’s added a little extra so you can disconnect from a Bluetooth device instead of Forget it entirely, making it much easier to, say, stop using a specific speaker and return to your iPhone’s built-in speaker.