I have created a workflow where HR submits a ticket to off-board an employee (custom field of End Date). I need to deactivate the user in Okta based on the End Date which is the tickets due date.

1. A Service Request is submitted with custom field End Date. 
2. With Expressions, the End Date modifies the tickets Due Date. 

What I need now is for the Okta account to get deactivated based on the due date (which is modified by the expression). 

How do I trigger the Okta account deactivation based on the Due Date? Help is appreciated.