How to unpair keyboard

[Meffesino]

Hello,
I currently have paired a keyboard with my retropie. I have paired my keyboard also with my iMac. Unfortunatelly the retropie is 24/7 online and when my iMac is off, the keyboard is connecting to the raspberry. When I start my iMac again, it is really an act to get the keyboard disconnected from the raspberry and get connected with the iMac again.

How can I unpair the keyboard from retropie?

I tried already the retropie-setup scrip by using:
sudo /home/pi/RetroPie-Setup/retropie_setup.sh

--> Configuration / tools --> 804 Bluetooth ...

• -- When I use "remove bluetooth device" it shows: "There are no devices to remove."
  I don't know why. It shows the same, when the keyboard is connected and when it is not connected.

• -- When I use "display registered & connected bluetooth devices" it shows
  "Registered Devices:
  Traceback (most recent call last):
  File
  " /home/pi/RetroPie-Setup/scriptmodules/supplementary/bluetooth/bluez-test-device", line 44, in
  <module>
  adapter =
  (...)
  "
  nothing to select and unpair.

Side information, which might help:
I have ps3controller installed too.

I also tried to disconnect it by using the documentary: https://retropie.org.uk/docs/Bluetooth-Controller/ , but the menu (or the results) are not the same as shown on this site.

Thank you in advanced for your support.
Best regards,
Meffesino

[AlexMurphy]

@Meffesino Try removing it via the command line. Here are some commands that you will need to use http://www.raspberry-projects.com/pi/pi-operating-systems/raspbian/bluetooth/bluetooth-commands

[Meffesino]

Sorry, this was not working....

pi@retropie:~ $ bluez-test-device remove E8:06:88:4D:25:43
-bash: bluez-test-device: command not found