Soon after the first steps in developing web applications with Eclipse WTP, developers often realize that the default context root of their applications is not exactly what they want. By default, the context root goes after the project name - if the name of your project is "HelloWorld" then it will be deployed with context root "/HelloWorld".
Setting the context root when creating a new web projectAs described in the Web Tools Platform User Guide, when creating a new web application, you typically use the "New Dynamic Web Project" wizard. Instead of finishing it on the first wizard page, you should click on the Next button to advance to the "Web Module" wizard page. There you can set the context root of the application by modifying the value in the "Context root" text field. If you wish to deploy the application in the server's root then simply give "/" as context root.
Changing the context root of an existing web projectTo change the context root of a web application that is already available in the Eclipse workspace, simply right-click on the web project and call the "Properties" action from the context menu. Then navigate to the "Web Project Settings" property page and you will find the text field where you can change the context root.
Depending on the server adapter you use, if your application is already deployed and started then you may need to redeploy it or restart it for the change to take effect.