On the top left side of the producer window you will see the "Output Settings" panel.
At the top you will see a preview window of what your current output looks like. Beneath the preview there are the Launch Output and Clear buttons. The Launch Output button will open your output in a new browser tab and the Clear will clear any posts from the current output.
While in Vidpresso you will also be able to hit the "Escape" / "ESC" key to clear the output.
Below the preview window you will be able to change any settings related to your output. If you're using the Ad feature you will be able to switch you active ad as well as update headlines in the stencil. This is also where you will be able to change which output style you're currently using.