How does the transaction takes place for exchanging our BTCs to $
Im quite sure it was not meant how to cashout at exchanges ;-)
I recommend to contact the exchange before trying to cashout such a high amount at any exchange.
Most times you run into withdraw limits...and your $ will be eventually get blocked for a very long time...
My experience with exchanges is quite mixed...
And you have to think about the question: To whom do you trust to hold 1Mio USD for you?
Exchanges are not Banks.
And even banks you have to select well in case you want to deposit high amounts.
Anyway the thread is obsolete.
OP seem to be not serious.