I have a website. Two years ago I installed vbullettin forum in my website. Despite of moderation the forum received only spam posts. I removed my forum from the website.

But google has indexed the forum and it still shows 404 pages not found error of my removed forum pages. Also some spam websites have linked to my forum pages.That is the reason why google shows them as 404.

How to remove pages from google's index completely.

Kindly guide me in this regard.