It's just usually editing the bit of code in your Theme. In your FTP file manager (like FileZilla), go to Public HTML --> WP Content ---> Themes ---> Thesis ---> custom and then find your css file. If I'm not mistaken I think it's titled style.css (or it could be custom.css too) Open that file, and now find the code for your sidebar. Basically you just have to find some piece of code their for your sidebar border and change it to "0px" (you can delete it too but to be safe it's better to just change it to "0" so as to not mess/confuse your code in the future). Hope that works. -Liane
Thanks for the reply. But I searched in custom.css(and even custom_function.php) , but was not available.
I don't have thesis theme so I can't look into it. Is there a live url then it would be easier to locate the css property.