How do I remove node URLs?
You must give a value for Default front page, and since you don't want to use node, you need to give another value for that setting. 


Enable the Path module that comes with Drupal 6 core, from admin/build/modules


  

Create a Page node, from node/add


  

Add the path alias you want to use to the node being created


  

Save it
Change the default front page, and put the path alias you assigned to the node you just created, on admin/settings/site-information


  

Save the settings


Now Drupal will use that node as front page.


  


If you installed the Vertical tabs module, the node edit page would appear different. In this case, you can find the path alias text-box under the URL path settings tab.


  


I used a Page node for the front page, but you can use any content type you want.