How do I reduce the size of my archive

I have an archive that is 821 mb. It was bigger but I deleted all the extra images WP created.

Is that too big for a 120 page site? It has images but they are compressed with SmushIt.

The reason I know the archive’s size is because I am trying to backup the site with a WP plugin called Duplicator.
Duplicator says it will give a warning at any size over 150 mb.

I also found some old backups from Updraft and deleted them, but they did not effect the size of the archive.

I read a post that said to look for files that say “core” and see if I can delete them. It said they are core dumps and I don’t need them. I don’t know what a core dump is so how do I find these large files and how do I know if it is OK to delete them.

Thanks

The disk space usage in cPanel says that the bulk of the files are in public_html