How can I disable the mouse key option on the login screen?

The mouse key option is currently turned on (by accident), so I can't enter the letter "o" on the login screen. Because of the inability, I can't enter the password, nor do the MacOS Recovery option (because it asks for the password that contains the letter "o"). How can I disable the mouse key option on the login screen and for permanently (it takes about 5 seconds to see the mouse key symbol appears to take effect; hence I can't use the numbers/letters at login: 7 8 9 u i o j k l m )?

[Re-Titled by Moderator]