Macbook Pro wants password to obsolete iCloud email address or else.

Hi guys, URGENT help required!

I have a Macbook Pro mid 2012 13''. On boot up I click on my icon and enter my apple id and it gets excepted and the machine proceeds to boot up. Once booted up, almost, instead of showong me my desktop i get a simlar looking screen as the original, this time asking for my icloud details. I put these in and it just won't have it. My details are correct but the mac isn't happy and won't let me in. I am pretty sure my mac is looking for a password assigned to an email address I no longer can use or access, it is **** bent on me typing a password for this email address even though i removed it quite a while ago. Because my Mac won't forget this old email address I am completely stuck in no mans land without being able to access my account on my Mac.

Heeeeeeeeeeeeeelllllllllllllllllllppppppppppppppppp!!!!!!!!!!!!!!!!!!!!!!!