Info automatically added at bottom of page

I’ve been looking and haven’t seen an answer to this problem, but I may not know the correct words to use for a search.

Someone who used to work with me set WordPress up to display a line of text, “Post your assignments over at the assignments tab,” and I cannot figure out how to get rid of it. It shows up only when a screen does not allow comments.

There is no plugin I can see that is controlling this. I figure it has to be set up in WordPress, but I can’t find it. Any help would be greatly appreciated. Thanks.