Just add your phone and it will overwite one of the added phones.

Yes, To delete the old phones, press and hold the pair button (if you can find it or get a new one and plug it in), turn the ignition to stage 1 (radio circuit) and wait 3 seconds then release the pair button then press again the pair button and wait 10 seconds, the car should then beep and the nav screen should say something like "phones deleted".

Never heard of this style before, I'd say you either have one of the following....

1: OEM BT with the cradle (and button) removed by previous owner (for some reason; cup holders???).
2: OEM BT retrofitted by previous owner and the cradle (and button) for some reason has been omitted.
3: OEM BT retrofitted with bemmannav BT kit by previous owner and the button is in the boot (trunk).

All of the above need to have the button located for any pairing to take place, look in the OEM place first for the 18pin connector and go from there.

You can not use the MFSW button to pair or delete phones, it's only for answering or hanging up the phone or using VR.

HTH

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Sept 03, M3, Silver Grey. Retro-fits: Modded Mk4 DVD Drive, OEM Bluetooth, VR Control, Rainbow Speaker Upgrade, Sony SOT Amp, HK Sub, CCFL, Intravee II, NightMode.