Student of secondary school (class 6 to 10) persistently misbehaves, disturbing the whole class, and slowing down class progress; what should be done?

I never had such problem - am a strict professor and never allow to gave these outbreaks 

no i will become a part of this rular i m best in teaching so i prafer to tech just

Students always have a reason to misbehave it is our duty as a classroom teacher to find out the root of the problems. It is important to always remember students are children and need to see you as human. In the classroom the rules apply to everyone however outside of the classroom spending time with the student to find out the issues could portray an easy fix, folr example they need to sit closer to the teacher or away form physical or visual distractions in the classroom. Sending the student outside to calm down not because they are in trouble but becasue they just need a break is very helpful in my opinion. This gives the class time to focus back on the task at hand and the student time to calm down before reentering the classroom.

At the beginning of the school year, the teacher should explain them the rules and procedures of the classroom. Once they violate them, there parents should be consulted promptly. Parents generally don't know about the misbehavior of the children. Most among students do not misbehave before their parents. If parents are non-cooperative, the teacher should inform the school administrator or principal and take him into confidence. Also, the teacher can take advice from his co-teachers who are teaching the same class and ask them the ways and means of controlling such students. In this regard a book by Harry Wong with the title 'First Days of School' is quite useful.

In our school I was part of a controling bahaviour community we created a system that help teacher to add behaviours for each student and then data will be collected and each student will have a record of bad behaviour and then the principal will take certain measures with students who have more than certain number of bad behaviour

Separate the students like mentioned previously. When class is in session ask them the questions, focus on them. Most of the time kids misbehave for the attention.

Can you move him/her to a different desk? Can you have him/her sit at the front beside you?

Such kids have more intellegence level.
I think he should be placed in front row and should be given special attention.
Interactive teaching method(participation of both teacher and students) shall reduce his time interval for mischief.