The document, minus the clutter
A bank statement whose last page is nothing but a notice about new fees. A washing machine manual in twelve languages when you read one. A scanned notebook where every other page is blank because the scanner captured the backs too. Remove pages takes out what you don't need and leaves everything else as it is, in the same order.
Two ways to mark pages
The first is clicking a thumbnail. A marked page fades and gets a red ✕, and a second click puts it back among the pages you keep. The second is the "Pages to remove" field: "4, 9-12, 20-" marks page four, pages nine through twelve and everything from page twenty to the end. The field and the thumbnails are linked – what you click shows up in the field, and what you type shows up on the thumbnails.
A check before you commit
The line under the field shows how many pages are being removed and how many will remain. The tool will not let you remove every page, since the new PDF has to keep at least one. Type a number the document doesn't have and you are told the range is outside the document.
Your original is safe
The result is a new file with "-edited" added to its name. The document you started from stays untouched on your device. The pages that remain are not reprocessed: text, images and fonts are the same as before. Everything happens in your browser and the file is not uploaded.
When another tool is the better choice
If you want only a handful of pages from a big document, Extract pages is quicker. To move or turn pages as well, use Organize PDF. To divide a document into several files, use Split PDF.