Well it's not that easy. You have to import the data to the database tables. Not move the whole tables to the database!
It's easy to delete. Use a ftp program and delete the program from the root dir and the admin dir. In phpMyAdmin you can delete the j17_osc... tables. Don't forget the program rule in j17_extensions.
Delete the edit's from the two index.php files.
Now the program is deleted. You can install again.