Adding google adsense to payment modules

[DrByte]

Just compare all the files on your server vs the files that come with Zen Cart. Then remove the files that aren't part of the Zen Cart package.

Here's one documented way to do that:
http://www.zen-cart.com/wiki/index.p...Obscure_Issues

Ok I must be stupid because I dont understand how to get the original files to compare with the original zen cart to mine?

The link I posted above explains it:

2. Run WinMerge or a similar Diff/comparison tool to compare all your site's files against a freshly unzipped copy of the same version of Zen Cart™. You can find the original release ZIPs here.

Note the link on the word "here".