It might be as simple as go to settings > permalinks in the wp admin and remove the trailing slash at the input box for custom structure

Here are the steps to remove trailing slashes site-wide. If you simply wish to remove the trailing slashes on posts only, skip to Step 2.

Important Things To Consider

• In .htaccess, the code between lines # BEGIN WordPress & # END WordPress may get reset by WordPress. Avoid changing code between those lines.
• Forcing removal of trailing slashes, causes a loop in example.com/wp-admin. You can avoid the issue by excluding directories RewriteCond %{REQUEST_FILENAME} !-d.

The following solution addresses those issues.

Step 1 - Update /.htaccess file

Add the following code before the # BEGIN WordPress line in your /.htaccess file. This redirects URLs with trailing slashes to URLs with no trailing slashes.

# Remove trailing slashes<IfModule mod_rewrite.c>RewriteEngine OnRewriteBase /RewriteCond %{REQUEST_FILENAME} !-dRewriteRule ^(.+)/$ /$1 [R=301,L]</IfModule>

Step 2 - Update Permalinks

As others have pointed out, you must also update your Permalinks (Settings -> Permalinks) to Custom Structure, and remove the trailing slash there. It removes the trailing slash on all your posts.

Try this:

# BEGIN WordPress<IfModule mod_rewrite.c>    RewriteEngine On    RewriteBase /    RewriteRule ^index\.php$ - [L]    RewriteRule (.+)/$ $1 [R=301,L]    RewriteCond %{REQUEST_FILENAME} !-f    RewriteCond %{REQUEST_FILENAME} !-d    RewriteRule . /index.php [L]</IfModule>

If it doesn't work try this one:

# BEGIN WordPress<IfModule mod_rewrite.c>    RewriteEngine On    RewriteBase /    RewriteRule ^index\.php$ - [L]    RewriteRule (.+)/$ http://www.domain.com/$1 [R=301,L]    RewriteCond %{REQUEST_FILENAME} !-f    RewriteCond %{REQUEST_FILENAME} !-d    RewriteRule . /index.php [L]</IfModule>