Login

You can open the wp-content/plugins/dw-question-answer-pro/templates/styles/default and open the question-submit-form.php file then remove the following code:

<?php if ( is_user_logged_in() ) : ?>
        <div><?php _e( "You doesn't have permission to post a question", 'dwqa' ) ?></div>
    <?php else : ?>
        <?php dwqa_load_template( 'login', 'form' ) ?>
    <?php endif; ?>