To erase packages, do not just delete folders you find with Internalz. WebOS uses the ipkg package management tool. In any Linux system that uses a package manager, bad things can happen if you skip using it. Here is a better way to delete packages on webOS.
First, you need the exact package name. Lets look for the AT&T Navigation app. This first command lists all installed apps, and then filters the results to only lines containing the word "navigation".
The first field is the name we need. Now we delete it with this command.
root@Pre3:/# ipkg list_installed | grep navigation
com.telenav.attnavigation - 1.0.2-38 - Telenav App and Service
Here is another example with the yellowpages app.
root@Pre3:/# ipkg remove com.telenav.attnavigation
Removing package com.telenav.attnavigation from root...
root@Pre3:/# ipkg list_installed | grep yellow
com.yellowpages.ypmobile.preload - 1.0-15 - YPmobile App
root@Pre3:/# ipkg remove com.yellowpages.ypmobile.preload
Removing package com.yellowpages.ypmobile.preload from root...