You still haven’t indicated the type of master socket you have , only No.4 should have A and B connected directly to 2 and 5, all the others the A and B connect is to the part of the socket that remains in the wall , and only extension sockets are connected to 2 and 5 of the consumer panel, if no extensions , you can either use the test port socket or insert the consumer panel and use the socket in that, if someone has connected A and B to 2 and 5 of the panel , it bypasses the plug and socket , so the panel would remain live even when disconnected from the body of the socket , making the demarcation point redundant , I’ve no idea why someone would do this unless the socket panel was faulty , otherwise when assembled the plug and socket would be making the panel ‘live’ anyway.
If it’s No.4 , then it could be you don’t actually have a master socket as such ( it’s an extension socket being used instead of a master socket ) or it’s a pre NTE5 type LJU socket….obviously if this is the only socket , then the A and B need to be connected to the part of the socket that a RJ11 phone plug would connect with…perhaps you could post a photo as how can wires on A and B ( marked as such presumably ) also be connected to 2 and 5 if not via a plug and socket arrangement .
If what you mean is that you do have a proper master socket ( any of the images apart from No.4 ) and that has the line from outside on A and B ( of the permanent portion that stays on the wall ) , and there is a cable on the removable consumer panel on 2 and 5 that runs to an extension ( or extensions ) that you do not use , so is it ‘safe’ to disconnect the extension cable from the consumer panel , then yes you can , if you don’t want extensions the consumer panel should not have any wiring on it at all.
