In Wordpress, each article must have a unique permalink. If you have 2 articles with the same title, the second article with have a "-2" appended to the URL. This "-2" will not be removed just because the original article has been deleted, and so to fix this, you'll have to edit the permalink (under the title of the page in the CMS https://share.getcloudapp.com/z8ud5xEB) to remove the -2.
If you remove the -2 and it adds it back when you click "ok" it, it means that there is another article with the same slug already. You'll need to delete, or change the slug of the original article, and then try again.
See this article for more details - https://wordpress.com/support/permalinks-and-slugs/