If you are talking about comments that you have made about photos that you added to your ideabooks, all you need to do is go into your ideabooks, click "edit", and then next to "privacy" check the box that says "make this ideabook private" and then click the "update" button at the bottom of the page. From now on, any image that you note and add to that ideabook will have its comments hidden from other houzz users unless you share it with them.

If you are talking about a facebook "like" you will need to go to your facebook page and remove the post from your wall...I think that will do the trick.