That’s not a master socket , it’s a BT66 , a socket is where a phone cord plug connects, a BT66 typically is where the external cable and internal cable connects together…the master socket on the other end of the internal cable inside the BT66 ….BT66’s are normally external ‘block terminals’ , not on internal walls .
As far as moving it , it’s Openreach not BT , search relocation of Openreach equipment, if there is no working service over it , and FTTP is available at the address , it’s basically redundant and can be abandoned/removed as it’s never going to be reused .
