This is from a book called: Imaan between the Salaf and the people of Rhetoric which is a Master’s thesis written by Ahmad Al Ghaamidi published in the year 2002.
He said regarding the Khawarij :
“The Khawarij: They are called such because they rebel against every leader with the belief that this is compulsory upon them and that it is not sufficient to follow them. Therefore they rebel and take for themselves place of Hijrah (emmigration) in order to oppose those who oppose them from the Muslims and to make war against them. And the Muslims according to them are disbelievers and polytheists except those who agree with them and pledge allegiance to them and seek protection from them until they hear the speech of Allah.” 
Therefore, those who say they are not Khawarij and that they are leaders therefore it is impermissible to speak about them let them reflect on this written statement which will clear up any doubts regarding them.