How to free account space?

I need to understand how can I empty my account space? 

Greetings and thank you for your message.

I have checked your account, and you currently have an active bronze subscription. With this plan, you get 10 GB available space. 

To empty the space, you need to remove the submissions where the uploaded files are stored. After you remove the submissions, please make sure you empty the trash as well:

Please let us know if you have any additional questions.