Removing Permalink Plugin without breaking site

Many years ago I installed a plugin called “permalink editor” which I have used ever since but apparently now has been abandoned so Wordfence has advised me to remove it.

I went into wordfence settings and set permalinks as “https://www.xxx.com/%postname%/”
so I assume a link that is currently https://www.xxx.com/test should still work when I disable the permalink editor, but it doesn’t. Some links still work but most don’t. Can someone help me sort this out so I can remove the plugin which I assume I don’t need anymore.