Hi Melissa

It looks like you've used the area selection feature to publish a portion of your document. The red box you see on the canvas refers to the portion of your document you have published. In order to remove this box you will need to un-publish the access link. You can do this by following these steps:

1.) Click "Share" > "Publish" 

2.) Click the trash icon next to the area selection link as shown here:

Feel free to let me know if you have any additional questions.