I don't use script-fu, but another possibility is to iterate the layers and delete those with a name that match "Frame*" (or whatever regexp will work in TinyScheme). Personally, I make a habit of calling my temporary work items (layers, gradients, brushes...) with a "#" so that they are easier to spot.
In python-fu you have an <Image> object, that has an array of <Layer> (unexpectedly called "layers"), ordered as in the layer stack, so the top layer is image.layers. Welcome to the 21st century
PS: sorta ninja'd by paynejk myself