How can I remove Validation from Date Attribute?

Document ID : KB000099878
Last Modified Date : 01/06/2018
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We recently updated one of our processes to set the ‘Actual End Date’ Attribute to today’s date when the Project Status is updated to ‘Complete.’ The issue we are now having is that when we update any attribute on the Details subpage (where the Actual End Date attribute is housed) we cannot save changes to the page because the Actual End Date doesn’t pass the validation. Can the validation be removed from this attribute?
Change Validation From, To and Default Date to [--Select--] and click Save you will get the error as below but notice that Rolling date option will become unchecked and if you click on the Save again, it will now save it without any validation in place. 

ERROR ODF-0008: Invalid Date format. Check the format to make sure it is correct.