If you want to remove the file extension from the URLs, then this tutorial designed for you, keep your close attention in the tutorial as I am going to share how to remove the file extension from URLs.
If your site URL is http://example.com/about.php and you want it to be like http://example.com/about, then use the code as suggested below.
Open the .htaccess file and copy paste below code at the end of the file. The .htaccess file is located in the root directory of your website. Below code will remove the .php from URLs.
RewriteRule ^about$ about.php [L]