How to properly remove old Bluetooth devices listed in the Bluetooth menu?
I don't know who directed you to do it this way but the &#8997; method is for troubleshooting/removing active devices.

As far as I know, this is how you unpair/remove a Bluetooth device:

&#63743; → System Preferences → Bluetooth → Hover over the device you'd like to unpair/remove → click the x to its right.