Remove the category from wordpress urls permalink /%category%/%postname% without a plugin

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To remove the annoying:
example.com/category/%category%/%postname%

and get the better:
example.com/%category%/%postname%

I added this line before the wordpress standard .htaccess code:

Options +FollowSymlinks
this is the old .htaccess contents:

[/crayon]

this is the new one

[/crayon]