I referred to your correct GitHub project:
https://github.com/lewisl/lewislevin-com
I use Hugo a lot, but it certainly looks like a problem that has nothing to do with it.
Render does not delete previously generated files.
I did a simple HTML add / remove and confirmed this.
Hugo does not support deleting public folders.
This will continue to be a problem when using Hugo with Render.
The fact that it doesn’t build after reconnecting to GitHub seems to be another issue.