Deleting the wrong page is easy
A tool that offers only a text box asks you to be certain about page numbers you cannot see. Off-by-one is the most common mistake in every PDF tool, and with deletion it is the most expensive one.
Here the range box and the thumbnails are two views of one selection. Type 4-6 and pages 4, 5 and 6 highlight. Click a page and the range text updates to match. Whichever way you prefer to work, you can see what is about to happen before it does.
Nothing modifies your original file — the result is a new download, so a mistake costs nothing but a repeat.