Clear Followers from Mission -> Get Base Success Chance

[Oniya]

Is there a function in lua to clear all followers from All Missions?
I have some problem - seems to be some addon do not remove followers after his calculation, cause of it when i try to use:C_Garrison.GetPartyMissionInfo(missionID);
Its returning me not base Mission Chance, but chance for current group,

Is there an opportunity to get Base Mission Success Chance other way or be sure Mission Party contains no Followers in it - to get right base chance

Thanks!