Select the cell or range with the drop-down
Go to the Data tab
Click Data Validation
In the Settings tab, click Clear All
Click OK
To remove only the drop-down arrow, uncheck In-cell dropdown in Data Validation
Click OK
To remove a drop-down from a table filter, go to the Data tab and click Filter to turn it off
To remove a drop-down from a form control or ActiveX control, right-click it and choose Delete
To remove a drop-down from a pivot table, adjust the field settings or remove the field from the layout