Problems with 'enlarging products'

[Onstar]

hello everybody,

 

 

I continue to track while people leave my site when they arrive.

 

I found 2 related problems:

 

1. Because of a typo, easypopulate created 2 categories of products

2. When you find the site and click on a product to enlarge, user will experience error 404 message.

 

 

here are my questions:

 

1. I found the right and wrong category in the database. Can i delete this category right inside the category?

2. How do I do that?

3. How do I fix the ' error 404' page?

 

Thanks.