posts that have been deleted are showing up in excerpt search

Hello,

When I run a search in my wordpress blog, and the excerpts come up for that search, posts that no longer exist are showing up as excerpts in the search. Though when I try clicking the ” continue reading” link, it takes me to a search box that says, “Not Found
Apologies, but the page you requested could not be found. Perhaps searching will help.” Some of these deleted post excerpts also have two thumbnail images instead of the usual one thumbnail. I’m using the plug-in SuperSlider-Excerpt to generate my excerpts.

How can I edit these excerpts to delete the ones that belong to deleted posts? Is there another plug-in to do this? Or can I access it through FTP?

Here is a link to show example of whats going on. ( fourth excerpt down )

https://www.culturalinquiry.org/blog/?s=sebald

Any help would be greatly appreciated, thankyou!!!