In module_strings :
Search and edit the following :
("faction_title_male_player", "Lord {s0}"),
("faction_title_male_1", "Count {s0}"),
("faction_title_male_2", "Boyar {s0}"),
("faction_title_male_3", "{s0} Noyan"),
("faction_title_male_4", "Jarl {s0}"),
("faction_title_male_5", "Count {s0}"),
("faction_title_male_6", "Emir {s0}"),
("faction_title_female_player", "Lady {s0}"),
("faction_title_female_1", "Countess {s0}"),
("faction_title_female_2", "Boyarina {s0}"),
("faction_title_female_3", "{s0} Hatun"),
("faction_title_female_4", "Grevinne {s0}"),
("faction_title_female_5", "Countess {s0}"),
("faction_title_female_6", "Sayeda {s0}"),
If you do not want them to have a title, simply remove the "Jarl" or "Boyar" titles and etc.
For example,
("faction_title_male_2", "{s0}"),
Will give them no title.