Bluetooth doesn’t show ‘disconnect’ option

Hello, i can’t seem to disconnect my Garmin device from my Bluetooth to be able to connect to another Bluetooth device. I wanted to connect to the Bluetooth in the car but the only option it gave me was to ‘forget this device’ for the Garmin. I selected this. However this then means the phone has actually completely forgotten the device and it didn’t show in the list to reconnect. I reset the settings so I could connect again but surely this isn’t the user journey as it’s awful! Googling this it looks like I should have an option to disconnect from a particular device which I don’t have. Any help appreciate as my Garmin watch is always on me so will always be connected to my phone.. meaning if I ever want to connect to anything else I have to forget it again??? Can’t be bothered with that each time. Thanks! Jen