My domain not redirect www to non- www using .htaccess

I am trying to redirect www (www.mushko.com) to non-www (http://mushko.com/) on my website but its not working and its showing this error:

ERROR: This site can’t be reached

www.mushko.com’s server DNS address could not be found.

I have tried this code:

    #redirect www to website root
    RewriteEngine On
    RewriteBase /
    RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
    RewriteRule ^(.*)$ https://%1/$1 [R=301,L]

But its not working.

Thanks