For unbridging the solder just get solder melted into a puddle then just quickly swipe backward between the two pads a few times and that will usually do the trick.
For using Ibus you will just plug a servo plug into the Ibus plug on your Rx, then run the power to 5v, ground to gnd, then the signal will go to a free "R" pad on the FC (Those are your "Uart's", which are basically like USB's on a PC). On the firmware side of things, just reflash the Fc with IBUS selected as the protocol then go into the ports tab and enable it to use "Serial Rx" on the number that you soldered your IBUS wire to (ie. if you solder the rx to R5 then you would tun on the serail rx for uart 5)
I hope that makes sense😂😂👍