How to connect Bluetooth device (headphones) to another computer without an access to currently connected one?

I have BT headphones, which remember to which computer they were connected. To connect them to another computer, I need to disconnect them first. Which means I need to open the first computer and manually disconnect them from it. Is this the normal behaviour of BT? Suppose I have 100 computers and mobile phones and I forgot, to which device I have connected my phones last time. What to do? Should I try each? Or maybe I forgot the previous device in my car. Should I really go down to the parking to disconnect? Is there another procedure to connect phones to the very computer I am sitting at?

Question by Dims on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.