I have an extensive amount of messages on my profile page; "thank you's" etc and I'm wondering if there is a way to delete old ones so that they don't add to filling up the website. Thanks for any and all comments.

No, there is no way for you to delete the comments. What happens is that as they get more some of them are later hidden (you can still click on a link to view them). Don't worry about the space though. All the comments together on your profile page would take less space than one single image. Space isn't really a problem at this stage.