Removing trailing slash in the home page url - .htaccess

Question

I've followed this: Mode Rewrite; with/without trailing slash on end of url? solution but it's not working out for my mybb site. I've tried adding it in the top and in the bottom of .htaccess ... but not working.
What could I be missing?
Here is my .htaccess, I've substitute mysite with example.com:
Options -MultiViews +FollowSymlinks -Indexes
<IfModule mod_security.c>
# Turn off mod_security filtering.
SecFilterEngine Off
# The below probably isn't needed, but better safe than sorry.
SecFilterScanPOST Off
</IfModule>
<IfModule mod_rewrite.c>
RewriteEngine on
RedirectMatch 301 ^/archive/index\.php/?(.*) /$1
# Some hosts need a RewriteBase specification.
RewriteBase /
# Google SEO workaround for search.php highlights:
# Make this rule the first rewrite rule in your .htaccess!
RewriteRule ^([^&]*)&(.*)$ http://forum.example.com/$1?$2 [L,QSA,R=301]
# Google SEO Sitemap:
RewriteRule ^sitemap-([^./]+)\.xml$ misc.php?google_seo_sitemap=$1 [L,QSA,NC]
# Google SEO URL Forums:
RewriteRule ^Forum-([^./]+)$ forumdisplay.php?google_seo_forum=$1 [L,QSA,NC]
# Google SEO URL Threads:
RewriteRule ^Thread-([^./]+)$ showthread.php?google_seo_thread=$1 [L,QSA,NC]
# Google SEO URL Announcements:
RewriteRule ^Announcement-([^./]+)$ announcements.php?google_seo_announcement=$1 [L,QSA,NC]
# Google SEO URL Users:
RewriteRule ^User-([^./]+)$ member.php?action=profile&google_seo_user=$1 [L,QSA,NC]
# Google SEO URL Calendars:
RewriteRule ^Calendar-([^./]+)$ calendar.php?google_seo_calendar=$1 [L,QSA,NC]
# Google SEO URL Events:
RewriteRule ^Event-([^./]+)$ calendar.php?action=event&google_seo_event=$1 [L,QSA,NC]
# Google SEO 404:
ErrorDocument 404 /misc.php?google_seo_error=404
# Default MyBB Rewrite Rules:
RewriteRule ^forum-([0-9]+)\.html$ forumdisplay.php?fid=$1 [L,QSA]
RewriteRule ^forum-([0-9]+)-page-([0-9]+)\.html$ forumdisplay.php?fid=$1&page=$2 [L,QSA]
RewriteRule ^thread-([0-9]+)\.html$ showthread.php?tid=$1 [L,QSA]
RewriteRule ^thread-([0-9]+)-page-([0-9]+)\.html$ showthread.php?tid=$1&page=$2 [L,QSA]
RewriteRule ^thread-([0-9]+)-lastpost\.html$ showthread.php?tid=$1&action=lastpost [L,QSA]
RewriteRule ^thread-([0-9]+)-nextnewest\.html$ showthread.php?tid=$1&action=nextnewest [L,QSA]
RewriteRule ^thread-([0-9]+)-nextoldest\.html$ showthread.php?tid=$1&action=nextoldest [L,QSA]
RewriteRule ^thread-([0-9]+)-newpost\.html$ showthread.php?tid=$1&action=newpost [L,QSA]
RewriteRule ^thread-([0-9]+)-post-([0-9]+)\.html$ showthread.php?tid=$1&pid=$2 [L,QSA]
RewriteRule ^post-([0-9]+)\.html$ showthread.php?pid=$1 [L,QSA]
RewriteRule ^announcement-([0-9]+)\.html$ announcements.php?aid=$1 [L,QSA]
RewriteRule ^user-([0-9]+)\.html$ member.php?action=profile&uid=$1 [L,QSA]
RewriteRule ^calendar-([0-9]+)\.html$ calendar.php?calendar=$1 [L,QSA]
RewriteRule ^calendar-([0-9]+)-year-([0-9]+)\.html$ calendar.php?action=yearview&calendar=$1&year=$2 [L,QSA]
RewriteRule ^calendar-([0-9]+)-year-([0-9]+)-month-([0-9]+)\.html$ calendar.php?calendar=$1&year=$2&month=$3 [L,QSA]
RewriteRule ^calendar-([0-9]+)-year-([0-9]+)-month-([0-9]+)-day-([0-9]+)\.html$ calendar.php?action=dayview&calendar=$1&year=$2&month=$3&day=$4 [L,QSA]
RewriteRule ^calendar-([0-9]+)-week-(n?[0-9]+)\.html$ calendar.php?action=weekview&calendar=$1&week=$2 [L,QSA]
RewriteRule ^event-([0-9]+)\.html$ calendar.php?action=event&eid=$1 [L,QSA]
<IfModule mod_env.c>
SetEnv SEO_SUPPORT 1
</IfModule>
#Added by Anurag
RewriteRule ^index\.php(.*)$ http://%{HTTP_HOST}$1 [L,R=301]
</IfModule>
<IfModule mod_deflate.c>
AddOutputFilterByType DEFLATE application/x-javascript text/css text/html text/xml
</IfModule>
AddType text/javascript .js
<IfModule mod_expires.c>
ExpiresActive On
ExpiresDefault "access plus 5 seconds"
ExpiresByType image/x-icon "access plus 800000 seconds"
ExpiresByType image/jpeg "access plus 800000 seconds"
ExpiresByType image/png "access plus 800000 seconds"
ExpiresByType image/gif "access plus 800000 seconds"
ExpiresByType application/x-shockwave-flash "access plus 800000 seconds"
ExpiresByType text/css "access plus 800000 seconds"
ExpiresByType text/javascript "access plus 800000 seconds"
ExpiresByType application/x-javascript "access plus 800000 seconds"
</IfModule>
<IfModule mod_headers.c>
<FilesMatch "\\.(ico|jpe?g|png|gif|swf|css|js)$">
Header set Cache-Control "max-age=800000, public"
</FilesMatch>
Header unset ETag
Header unset Last-Modified
</IfModule>
RewriteRule ^(.*)/$ /$1 [L,R=301]

Answer 1

Try adding this rule just below RewriteBase / line:
# remove trailing slash
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{THE_REQUEST} \s.+?/+[?\s]
RewriteRule ^(.+?)/$ /$1 [R=301,L,NE]