Showing a logout link into a theme
Showing a logout url into a theme can be done with the wp_logout_url() function. This function can be placed anywhere into your theme files and accepts a custom url as optional parameter.
If the redirect parameter is not used, users will automatically be redirected to the page you've selected into the settings panel.
Example usage: logout and redirect to current page.
<a href="<?php echo esc_url( wp_logout_url( get_permalink() ) ); ?>"><?php _e('Logout', 'posterno'); ?></a>
Example usage: logout and redirect to another page by ID
<a href="<?php echo esc_url( wp_logout_url( get_permalink( 5 ) ) ); ?>"><?php _e('Logout', 'posterno'); ?></a>