Tower of God Wiki talk:Q&A/@comment-4076672-20120602134641/@comment-4076672-20120628125158

You can't turn down a ranking since it's imposed by the Ranking Bureau. It's like a student may not feel he deserves his score of 70(wants something higher) but the teacher decides the score is 70.

But yes, you can reject an opportunity to increase it, if that's what you mean. ^^