Data Shuttle not deleting rows

Hi all,

Im new to data shuttle, implementing my first workflow.. overall its working fine, but what its not doing is deleting records when I attach new data to my source sheet. The scenario is, the source sheet contains a row thats not in the updated data. My expectation is when data shuttle runs it finds a target row where the unique identifier no longer exists in the new data and it deletes it in my datatable. Im not finding an option for that action in data shuttle.. what am I missing?