RewriteEngine On
# AJAX EXCEPTION
RewriteRule ^ajax/contact\.php$ - [L]
RewriteRule ^ajax/service-enquiry\.php$ - [L]
RewriteRule ^ajax/training-register\.php$ - [L]
# REMOVE .php EXTENSION
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.php -f
RewriteRule ^([^/.]+)$ $1.php [L]

# FORCE REMOVE .php
RewriteCond %{THE_REQUEST} \s/+(.+?)\.php[\s?] [NC]
RewriteRule ^ /%1 [R=301,L]

# SERVICE DETAILS
RewriteRule ^service/([^/]+)/?$ service-detail.php?slug=$1 [L,QSA]

# TRAINING DETAILS
RewriteRule ^training/([^/]+)/?$ training-detail.php?slug=$1 [L,QSA]

# BLOG DETAILS
RewriteRule ^blog/([^/]+)/?$ blog-single.php?slug=$1 [L,QSA]

DirectoryIndex index.php

Options -Indexes