Put your document in order
Open a PDF, wait for previews, and use the arrows to rearrange pages or remove a page. Export creates a new file without overwriting the original.
Example and limitations
To fix a document ordered 3,1,2, move the first page to the end. Previews are thumbnails only; export copies original PDF pages rather than rasterizing them.
What about signatures?
Editing may invalidate digital signatures. Keep the signed original.