Because you didn’t use the Package Manger to install you can’t use “Add/Remove Software”. Perhaps next time you install use the Software Search. Anyways, to uninstall Netbeans 6.1 see the instructions here: NetBeans IDE 6.1 Installation Instructions
Basically:
To uninstall the IDE:
Shut down the IDE.
In the IDE installation directory, run the uninstall.sh file.
To uninstall GlassFish/Tomcat together with the IDE, at the Summary page make sure that the correct versions are listed and check the appropriate checkboxes.