Add to .htaccess of your web main root folder
Use www in web url
# FORCE www IN URL
RewriteEngine on
RewriteCond %{HTTP_HOST} ^domain\.com [NC]
RewriteRule ^(.*)$ http://www.domain.com/$1 [L,R=301]
Disable www in web url
# DELETE www IN URL
RewriteEngine on
RewriteCond %{HTTP_HOST} ^www\.domain\.com [NC]
RewriteRule ^(.*)$ http://domain.com/$1 [L,R=301]