You should be able to make the field a Date type and then present it as a short date using the built-in date formatting option. If Tableau isn't recognising the field as a date type, right-click it in the left-hand pane and choose Change Data Type, then Date. Right-click on the field in the left-hand pane and choose Default Properties -> Date Format to acquire the abbreviated date format.
Here's an example of how to use DATEPARSE:
DATEPARSE('dd-MM-YY', [myDateField])