Closing entries by due date. Do I use disable?

Our due date for submissions is today at 5pm.  How do I close entries?

You can manually enable/disable your form, please check this guide: https://www.jotform.com/help/180-How-to-Enable-Disable-a-Form 

You may also disable the form on certain date, please check this guide for more details about it: https://www.jotform.com/help/137-How-to-Limit-Submissions-in-a-Form 

I hope this helps.