Possible? Yes, with custom code. Formidable does not provide a REST endpoint for deleting any entry, let alone all entries probably because it's a cybersecurity risk. To accomplish what you want, you would have to create a custom REST endpoint and make sure you built in ample security to prevent unauthorized users from deleting all of your data. As a developer, I would not accept a project like this because of the inherent vulnerabilities and risk of data loss.