Wordpress slugs autonumber issue

I am having an issue with page slugs…

I created a page with a slug that was similar but not identical to the page title. Next, I modified the title and the slug of that page. Then I created a subpage using the same title as that of the original first page which created a slug appended to slug-2. Manually overriding the slug to remove “-2” didn’t work, so I deleted both the parent page and subpage then recreated them anew. Now the subpage slug is appended with “-3” (without quotes). How do I override WP automatically appending slugs according to which version it thinks it is?

Note: These are static pages, not posts.

Your thoughts are appreciated, thanks.