Easy way to remove multiple hard-coded Adsense ads from articles?

Hi everyone, sorry if this has been posted before (and if I’m posting in the wrong area) but I couldn’t find anything in my search.

I use Google DFP Small Business to serve ads from a variety of networks, using Google Adsense to sell the remainder. These are all in the header and sidebar. However, I also have a Google Adsense 300×250 unit appearing in some of my articles, e.g. at the bottom below the content and above the comments.

This code was pasted in directly to the post editor, and is not controlled through a plugin or hard-coded into the site’s backend. The code hasn’t been pasted into every post, but nevertheless quite a few of the archives articles. An example is here (see bottom of article): http://www.urbanghostsmedia.com/2011/05/urban-decay-9-ghost-stations-abandoned-subways-rapid-transit-systems/

This was done when I was very new to WordPress/blogging, and didn’t know there were plugins available to control this sort of thing. Stupid I know, but we live and learn!

I have now installed Easy Adsense to manage an ad at the bottom of every post, and to test out various formats to see what works best. But I can’t activate it until I’ve removed the ads that currently appear in certain articles, as I might be in breach of Google’s terms and conditions when an additional ad appears (some articles have more than one Adsense ad pasted in, and I know Google allows three max).

Sorry to be long winded! My question is: is there an easy way (plugin or hack) to disable the Adsense code that’s currently hard-coded into some of my archives articles, so that I can then go and activate Easy Adsense? Or am I going to have to trawl through each post and manually remove the ad code where it appears?

Thanks massively in advance for your help!