Press 1 & 6 on your Ford Radio MK7 radio & you should get info scrolling on the LCD, enter the V code IE V123456 into this calculator & you can get your code for free. On older Stereos, The M code is printed on the label on the side of the radio, so remove it & you will see the code to enter on this site.
Essentially, to get the speedo to read your mileage again once tacho is physically removed , you need to source & fit a bypass loom, available from Henry Ford himself. The part number is 3C1T-10B942-AA & the “finis”code is 4522300. Is the part still available ? if not , just 2 connectors appear to be linked in the grey tacho plug (yellow & white with purple tracer).