Dear Maintainer, Without a back button, any errors made are difficult to correct. There is also no way to not select an option on the page "Do any of the following apply to this report" once an option is selected.
The best solution is to close reportbug, start a new instance and provide your correct inputs there. With a back button, going back and changing previously input information might force reportbug to discard information that you may have already input in a later step of the dialog. This is problematic (bad user experience), so there are no plans to implement it. Closing. This is fixed in newer versions (since reportbug 11.3.0). In older versions you can unselect an item by holding down the Ctrl key when clicking.
Please do not send private email. Keep the bug in CC. Thanks. If there is information in the first attempt that you want to keep, you can start new reportbug instance before closing the first, and copy and paste the relevant information. The difference between the two cases is that users are not surprised by unexpected information loss.