For reference, I have attached the screenshot showing the problem and the expected result.
Regards,
Here is the screenshot link: https://imgur.com/a/1VZxgdL
After going through the source code, I came across blacksquare which was a QED symbol redefined. But I don't know how can I remove the square box after the example. Which file should I edit. Btw the source code is available at https://www.latextemplates.com/template ... range-book