I have the cPanel access to a website but no wordpress login info. So I wants to change a widget content in the website.
How can I change it through phpmyadmin. Where are that widgets sidebar data actually stored? Is it inside wp-options table?
Widget options are stored in the options table under 'sidebars_widgets' as a serialized array. See this post for a longer explanation.
Changing the field per PHPMyAdmin is not recommended, use PHP, get_option() and update_option() instead, WordPress will take care for correct serialization then.