Looks like you have to have remote start, or go get a new admin key from a dealer.
Pulled these from the owner's manual:
I accidentally programmed all
keys as MyKeys™ • Vehicle has a remote start system
that is recognized as an admin key.
Refer to the Using MyKey™ with
remote start systems section
Note: For all vehicles with remote start installed, it is possible to
program all original vehicle keys as MyKeys™, in which case, you will
need to use your remote start system to reset all MyKeys™ as admin
keys by doing the following:
1. Enter the vehicle, close all doors.
2. Remote start the vehicle using your remote start fob.
3. Follow Steps 1-4 in the Clear MyKey™ section.
To reset all MyKeys™ as admin keys do the following:
1. Turn the vehicle on using the admin key.
2. Press SETUP or select/reset stem until PRESS RESET TO CLEAR
MYKEY is displayed.
3. Press and release the RESET button or press and hold the select/reset
stem until HOLD RESET TO CONFIRM CLEAR is displayed.
4. Press and hold the RESET button or select/reset stem until ALL
MYKEYS CLEARED is displayed.
If you don't have the owner's manual, it's available here: https://www.fleet.ford.com/maintenan...ls/default.asp