i am a retired school teacher. I choose to retire when i am when i am  eligible for private or public pension benefits
Is there any reason why you would want to retire at that time?  Do you not enjoy teaching?
I love my job i just do what is right for me. After all  retirement with a pension should be considered my right 
I agree.  You have earned it, and it wouldn't be right for you to keep the job if you no longer need it.  Better to make way for someone who does.
DO you think pension which is a defined benefit plan  where a fixed sum is paid regularly to a person is bad. Some people says it is
No.  Even one of America's Founding Fathers, Thomas Paine, thought a pension should be paid out to elders, and even young men unable to find work.
You might be confusing Pensions with  severance pay. the former is usually paid in regular installments for life after retirement, while the latter is typically paid as a fixed amount after involuntary termination of employment prior to retirement