I recently wanted to remove the extensions from my page for make the URLs more search engine friendly.
You can enable RewriteEngine and set as following
RewriteEngine On RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^([^\.]+)$ $1.php [NC,L]
For GoDaddy users:
Options -MultiViews RewriteEngine On RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^([^\.]+)$ $1.php [NC,L]