How to update the plugin?
If you use a too old version and see update warning you should:
1. Delete the plugin folder from wp-content/plugins using FTP or your host file manager
2. Upload new version using FTP or WP plugin upload tab (from wp-admin)
For all other updates you can easily do all from wp-admin:
1. Deactivate the plugin
2. Delete the plugin
3. Install new version using WP plugin upload tab (and activate it)