My free form upload limit is done, if I delete all the submissions will it still be over or can I still use the form?

I have created a free form. It has reached it´s limit of uploads. Can I delete all the past submissions and keep this form running, or if I don´t pay it will be disabled ?

For file storage, yes, deleting submissions that have files attached will reduce the storage total.  Remove enough files for your account to be within its limits again and your form will remain active.