Hello @ruinous101
Thank you for reaching out and I am happy to help!
All images converted with the web converter tool are sent to a third-party server maintained by the W3 Total Cache team which reduces resource consumption and allows for a large number of conversions in environments where resources can be limited such as shared hosting. Images sent to the W3TC server for conversion are only held temporarily and no permanent information is kept on the server regarding the images.
WebP optimizations with the Image Service tool do not replace the original image file and all conversions can be reverted without any loss of data.
Therefoe, if you delete the original image, the webp will no longer exist as W3TC uses rewrite to serve tose images as webp.
Thanks!