Sometimes, I accidentally put a grade - using a rubric - for the wrong student.  Is there a way to "undo" the grade, clearing out the rubric so no grade is recorded? 

I can change the grade to a zero, but that makes it look like the student received a zero grade on the assignment, which would (understandably) bother many of my students.  When I have to do this, I also put a note in the comments explaining it, but I'd rather avoid this issue completely, if possible.

Thanks in advance for your consideration!

Jamin