What is a locust
who is the first democratic president of rsa

Locus are a larger version of a grasshopper. When they breed they do it abundantly and they can cause serious crop damage when they fly in swarms. By the way this would be more of a science question.  ;)

Your second question is a history one:  I believe the answer is Nelson Mandela. He was the first democratic president of  the Republic of South Africa.  He was "sworn in" in 1994 at the age of 74 or 75 I believe.

eliminate individuals who opposed his rule

maybe you need to work on the pipes in the house. i am just saying this because you did not give any details.