Why is it that it always say "running out of storage"?

Why is it that it always say "running out of storage" even though I've already deleted a single form with numerous responses? Thank you!

The message you're getting is related to the number of submissions. As of right now, you have 80 submissions this month. The limit for the free plan is only up to 100 submissions per month. 

Please take note that even if you delete the submissions, the monthly submission counter will not be affected. The counter resets back to 0 every first day of the month.

Hope that helps. If you need further clarifications, let us know. Thank you.