What is the best way to handle when somebody interfere in your official matters?

i would confront him and listen to why he really thought he must interfere.

he might have a good reason ,just keep the communication chanells open.

if his interference isn't justified then i would politely ask him not to do it again.

Maintaining own with calm and tactfully avoiding conflict,try to rind out the actual reason of interfare.If it is legal then informing boss and coordinate him/her.If the stranger is wrong in wrong way try to understand him/her to stop that activity.If he/she donot obey then take actions as per official rules and regulations.

It depends if the reason of interferance is for my favour I will listen to him and if not just ignore.

Explan politely to him that you are taking care of this issue and if his assiatnce is required, you will let him know

Try to ynderstand his point of view, and explain best practice solution with referances :)

I will listen to him with calmness and do what will be the best in my opinion.

ignore him.

If someone is interfering in official matters, means that you have a loose ball left somewhere or that you dont have management skills to tackle such situation. 

Explain politely, if still it fails then there is always more than one way to skin a cat alive....

Discussion is a key towards resolving such issues.