LANG_F1 >> LANG_F3 >> LANG_F14

LANG_F3

LANG_F4

LANG_F5
LANG_F10 >> If I send a friendly contract termination, does the manager have to accept it?

LANG_F12: 
LANG_F11 YES NO LANG_F13
LANG_F9: 4117

If I send a friendly contract termination, does the manager have to accept it?

No, he can reject it if he doesn't want you to leave. However, he only has 30 days to answer (accept/reject). If he doesn't respond after 30 days, you can leave for free.

This helps players with long contracts get out of a team where a manager has quit playing.