DEX- Delete function

You can choose which type of resource you want to delete and then paste the "id" for the record, then touch the delete record button in red, and it will remove that record from Data Exchange.

 

To get the ID you will run the API for the resource and possibly building/student/date you are interested in.  Then copy the id.

Touch Delete Record in Data Exchange and paste the record id in and set the resource to what you want to delete.  Then press delete record.

You can do this for the records you want to remove and then rerun your validations.