Can we change the connected WABA number?
Yes, you can click "Reset" to you restart the embedded signup flow of your WhatsApp channel. The old WABA channel will be archived and a new WABA channel will be created after reset.
You could then click "Start WABA Setup" to start the WABA set up with the correct phone number or Facebook Manager again.
Please click here to see more details about the Standard Procedures of WhatsApp Channel Reset and Terminatation.