This is beyond annoying at this point. I keep getting this popup each time I close my web browser. Is there any way for me to stop this?
In CCleaner Options...Smart Cleaning.... do you have it turned off already?
As Hazelnut says,
I suspect that you may have 'Prompt me to Clean on closing' set for one or more of your browsers.
You can change the option(s) or turn it off.