Update review on Google Play after refund
Found this page that seems to address your issue. Maybe try to delete the review whilst on your computer if you've been trying on your phone or vice versa. It does say ''Note: You can only review apps you have previously downloaded and installed. When you download an app, it's linked to your Google Account. '' I'm wondering if the link between your account and the app is only deleted if the app was a paid app. Because I have previously downloaded free apps then deleted them from my device and the link between my account and the app is still present. 

Hope this helped

link to google support page