How do I stop registrations?

Do you want to stop users from submitting form?

Yes it is possible to achieve your requirement by disabling your form. You may like to take a look at the following guide on how to enable or disable form:  https://www.jotform.com/help/180-How-to-Enable-Disable-a-Form 

Please note that you can also set submission limit in your form as well. You may like to take a look at the following guide which should help you: https://www.jotform.com/help/137-How-to-Limit-Submissions-in-a-Form 

Hope this helps.

Do get back to us if you have any questions.