Are there Polyatheistic atheists who reject many gods as well as monoatheistic atheists..?

Of course. Then there are the T-atheists who only reject gods whose names begin with T. There are naturally other mono-literal atheists, who all insist that their choice of letter is the correct one.

Hello does it matter if you are an Atheist you do not Accept that GOD or GODS exist in reality so why do you need a descriptive term to denote the quantities of gods not accepted to exist the term atheist by definition is not accepting the god concept as a whole to say one rejects one god but not another is not atheist but rejection of types of religion to say an atheist only reject religions who have a one god concept is not atheist your question is not logical by the mere definition of atheist but thank you for your question

Being an atheist means not believing that any gods are real.

Was that too complicated for you to understand?

Any Atheist doesn't believe in any God or Gods at all. It isn't, "Oh, I just don't believe in the Christian God, but the rest of them are totally real." It's, "I don't believe in any gods; if you show me definitive proof, I'll change my mind."

I reject all gods including the god of the Knights Who Say "Ni."

Yes, yes there is (in some cases).