Yes, a mod or asst mod can delete on stock specific or even non-specific stock boards. Look at the post in question, and on the right bottom of the screen you'll see a small, red 'X'. Click on that. You can also do it when you first click on a board and the last 50 posts show up. You'll see the same red 'X' on the right of each and every one of those posts. Same thing, click on the the appropriate 'X' to delete it.

Hope that helps.