Removing the prefix (.html) from URLs
If you would like to remove the prefix from page addresses you need to add a specific line to the file 'config/config.yml'. Navigate to 'public_html/config' and edit the file 'config.yml'. If the file doesn't exist, create it. Add the following line to the file.
contao: url_suffix: ''
Rebuild Production Cache
Once you have added the previous code to the 'config.yml' file, on the Contao Manager under the Maintenance section click the 'Rebuild Production Cache' button. Once it is finished you are finished and the prefix will have been removed from page URLs.