Removing an empty drop down menu

I need help removing an empty drop down menu. 

I added some cells to my spreadsheet after placing a drop down menu in a cell.  Now the cell where the drop down was still shows an arrow beside it for a drop down, but there are no items listed.  I want to get rid of the drop down arrow beside the original cell that now no longer has a drop down.

I did go through the Data tab > Data Validation and clicked on the "Clear All" button.   However the arrow still appears beside the cell.  How can I get rid of it?

Thanks.