In general option in wordpress, I have changed the wordpress directory to be on http://mywebsite.com
but wordpress dashboard is still in htpps causing mixed content
There is a setting in your wp-config.php file that directs all admin traffic over https. You would need to disable that option for your admin panel to work correctly.
FORCE_SSL_ADMIN
needs to be false:
define('FORCE_SSL_ADMIN', false);
solves the issue. See relevant WordPress Codex pages: