How anger is developed? Most of the time I experience the situations that provoke  my anger.
I hate people. How  to overcome  this?how  to let go anger?
Generally speaking anger can be the result of any/all of the three root kleshas. They are:


not knowing the full reason for our anger (moha)
holding on too hard to something (raga)
lacking compassion for others (dvesha)


Mindfulness can help easing the first two kleshas, by investigating the cause for your anger, and to examine whether your anger is caused because someone/something is getting in the way of your attachment. 

Mindfulness can also help you identify any hindrances to develop understanding or non-attachment. 

Lastly, metta bhavana meditation can also help in easing your anger, by developing warmth towards others (the opposite of anger, essentially), and by  seeing the others side of things. It may be helpful to both you and your surrounding, and can contribute to a more objective or balanced outlook on things.