Ads by exstra coupan

Hi,

 I recently Installed Win7 Ultimate on my HP smal form factor PC, Am using Google chrome on it. I have norton 360 as antivirus software.

Recently my computer has severly affected with malware called "Ads by Exstra Coupan" where ever I click so many pop ups opening. Am not much about a software guy, I did those basic things But I coudnt remove using manual clean also with the help of malwarebytes.

Need help please

Thanks in advance

Dinesh