Delete an assignment created with "New Assignment" button in Assignments

We are using Moodle 1.9. A teacher accidentally created an assignment using the "New Assignment" button in the Assignments under the Activities block. She wants to remove the assignment, but there does not seem to be a way to do so. It only appears when one looks in Assignments in the Activities block, and there is not a way to delete it there - no "black x" or anything else. I can identify the URL of the assignment. Would there be a way to delete the related file that might be the resolution to the problem? Any advice would be appreciated.