A know-it-all or know-all is a person who constantly presents their input as though they were professionally trained, schooled or have firsthand insight into subjects when it is evident this is not the case. A know-it-all will quickly reject opinions, suggestions, thoughts and commentary from others as incorrect, nonsensical and disruptive.
The German word Besserwisser is also used in some languages, literally meaning "better knower".
References
Know-it-all Wikipedia(Text) CC BY-SA