A Phoronix reader and developer, Peter Wu, wrote in to share information on how he's reverse-engineered the Logitech HID++ protocol used by the Logitech USB receivers and he's also developed an unpairing tool. There's also another utility he points out called Solaar for unifying devices.
A small utility was made by Benjamin to pair new devices to one receiver, but that one has some issues: 1) it does not provide feedback 2) it is unable to unpair a device.Solaar comes down to being a Linux device manager for the Logitech Unifying Receiver that can be controlled via the command-line or from a GUI. Various features are supported like reading the charge status on the K750 Solar Keyboard, toggling the FN key state on some Logitech keyboards, changing the DPI for Performance MX Mouse, and smooth scrolling on select mice.
In my article "Logitech Unifying for Linux: Reverse Engineering and unpairing tool", I show how to reverse engineer the Logitech HID++ protocol as used by the USB receiver and present an unpairing tool, ltunify.
Hereby I also want to bring Solaar into attention. Solaar is a more sophisticated program for Unifying devices that I wish to encounter before going the reverse engineering route.