How to delete submissions without deleting the form?

It says I am almost out of submissions.  I just deleted one form that had almost 200 submissions.  How do I delete all the submission from my other forms but still keep them active?  I don't need them to be kept on file.

I checked your account and you have 258 Total Submissions. To delete the submissions and keep the form active, please follow this guide: https://www.jotform.com/help/377-How-to-Delete-Form-Submission-Data

Keep in mind that deleted submissions are not recoverable. 

I hope this information helps. Please contact us again if you have questions.