404nerror pages that don't exist

i have loads of 404 errors to pages that don’t exist & some of the URL’s are https://www.example.com/image-2, or /screen-grabs. I dont have these images or URL’s on my site any more. Is there a way to delete these I was told about .htaccess but don’t know how to use it. I enstalled a 301 redirect plug-in but if the pages don’t exist then where do I redirect them too.

Would really appreciate some help

Thanks