Sure thing, but if you’re having trouble and need some help, feel free to e-mail me at kevin no-spam at woolf dot com.
To uninstall, just delete the helloone template and skin directories in your default package. Magento will then default back to your default theme. You can find them at app/design/frontend/default/ and skin/frontend/default/ folders. There is nothing in the database to delete, but you should also change the settings in System–>Configuration–>Design under Templates, Skin (Images / CSS), Layout, and Default all to “default”.
Seriously, the HT themes are pretty good–not perfect–but pretty good. Magento is just so versatile and so configurable, and it provides several ways to produce the same effect in a stores. I recommend to all to get the Magento book or visit the forums for Magento questions and answers. The learning curve for Magento is steep, but put in three weeks to study the system and file structure and you’ll be a pro.