Just make sure that you power down the whole system (unplug from the mains) before you start disconnecting.  This includes any beolink adaptor boxes that are being used, if any.

I am not sure what type of junction box you are using but you would be best advised to open it up and see if it's possible to easily disconnect the cable that you wish to remove.  If it's one of the very small junction boxes, then you'll need a special tool to push the wires back onto the terminals.  You might need to cut back the individual wires before reconnecting any.

EDIT:  You may find page 133 of this handbook useful: 

Assumed it is one of the small junction boxes, my experience is that it would be best to clear it and connect the wired as from scatch.

However, be sure that you have sufficient cable for this where you are working.

As Guy wrote - disconnect all ML devices before you start.

Another option would be to keep the ‘BS9000 cable’ in the junction box - and make an extension from there with a new box (you’d have to cut off the plug, then.

Or get a ML Distributor box...that would be easier ;-)

 
MM

Yes, it’s the small junction box, and I’ve got the tool to press the cables in place. There’s already a junction box behind the new placement, so no problems with that connection. I will try remove the old cable from the other junction box, but as there are other cables as well I’ll probably need to cut all cables and connect them again.