Fatal Error: Call to undefined method

Getting a fatal error message: call to undefined method EWWWIO_Imagick_Editor::remove_exif() in directory/etc/thumb.php on line 472

/** Remove Exif from the image
*
* @supports 3.5.1
* @access public
*
* @return boolean|WP_Error
*/
public function remove_exif() {
try {
return $this->image->stripImage();

} catch (Exception $e) {
return new WP_Error( ‘image_remove_exif_error’, $e->getMessage() );
}
}
}

Appreciate any help.

https://wordpress.org/plugins/ewww-image-optimizer/