Hello Belle

Thank you for reaching out and I am happy to help!
Can you please apply this fix and change the line of the code in the plugin files: https://github.com/BoldGrid/w3-total-cache/commit/bbaa490e8bfa0708f198760cd052a656ac4b47ef

Once applied, please reload the W3 Total Cache Dashboard and try to disable the W3 Total Cache.

Thanks!