What do I need to do to stop Amazon products being displayed on my iMac permanently. I have decided to never purchase products from Amazon. How can I program my iMac computer preventing any data from Amazon entering my computer. Please explain in gre

With Little Snitch you can block their IPs...

https://www.obdev.at/products/littlesnitch/index.html

Where are you seeing these products?

I am guessing it is just a google ad.

Yeah, could be, or a chance it's Adware. :)

If you are talking about Ads in your Web Browser I would recommend using a Browser that you can use a Ad Blocker in. I myself have been using the Brave Browser and it has a very effective Ad Blocker built in. And I have not been bothered by Amazon Ads as I browse! There are extensions that you can get for Chrome, Firefox and such but with Brave it is built in. It is based on the open source software that Chrome uses but it is not Google Chrome. I do not include Safari because Apple has dropped support for Ad Blocker Extensions and gone to the Content Blockers which are not very effective. You might want to also get the Duck Duck Go suites from the various stores and that is available in the Mac Store Also. That will block 3rd Party Cookies and force sites to load in a HTTPS Connection.