How to remove specific pages from website that are not in my dashboard pages

Hello,

I have at least 1 page and perhaps more, which are still in my database that have been permanently deleted using dashboard. This page(s) can be accessed by directly typing them in the URL (ie https://www.mywebsite.com/?attachment_id=108) and worse is they are referenced by search engines. Since I no longer use this page(s), how can I remove then from my database, or better, give a redirect to the actual page the search engines should now use.

Thanks for any help.

-Rodger