JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
This is because you've reached the storage limit, it is about the number of submissions that you can store in your account:
This limit is only for free accounts and you need to delete your oldest submissions in order to avoid getting notified about reached your limits.
You can also download your submissions and all your info and you will not lose your data, here is the link that will help you to download all your data at the same time: How-to-export-all-of-your-data-at-once
You can also avoid deleting your data and upgrading to the storage plan so you will not need to delete your submissions:
Or you can also upgrade to any other plan in our pricing page: https://www.jotform.com/pricing
Hope this helps.