there are two ways to this regardless of license. This works on the free version. If you are viewing the entries in the admin area, change the screen options to change the number of entries to see at once. The screen options button is on the lower right corner. The Formidable logo floats about the button. Click the button and the screen options panel opens at the top of the page. Change 20 to whatever number you want. This is how WordPress works. If you filter the entries by form, you'll have a "Delete All Entries" button to click for that form.