Delete the date to request a requirement be reviewed by a certain date

In the details window of the desired requirement, click the next to the current due date to remove it. Alternatively, in the Reviewers tab, click on the next to the current requested date to remove it. A date can still be added and changed after a requirement is sent for review. If a date is not appearing, there may be no previously selected day or there are no reviewers added. 

Users will need to be the requirement owner or co-owner, and have project permissions to view and edit the requirement to perform this action.