Making a new post in your thread will bring it back to the first page. This is known as "bumping" a thread, which is a pretty common occurrence on most forums. Just make sure to space out your bumps to once every 2-3 hours or so.
To removed an attached image, go to the "Edit Post" link at the bottom right corner of the post in question. From there, click "Go Advanced" and scroll down a bit where you should see an option to manage attachments. You can remove any and all attachments/images from there.