Can the deleted pages be recovered from the file?

No. The output is rebuilt from the pages you kept, so the removed pages are not present.

The original file on your device is never modified.

organize

Delete Pages From a PDF

Remove the pages you don't need and download the rest.

Runs in your browser

Deleted pages are genuinely absent from the output file, not merely hidden. At least one page must remain.

/extract-pdf-pages

/split-pdf

/reorder-pdf-pages

Can the deleted pages be recovered from the file?: No. The output is rebuilt from the pages you kept, so the removed pages are not present.
Can I undo?: The original file on your device is never modified.