How do I delete files from a protected application?

I'm trying to uninstall an application using TrashMe and I keep getting the following message when dragging the application folder into the TrashMe window:

"Protected applications cannot be trashed. Please check your Preferences to unlock this protection."

I have already downloaded and installed the TrashMe addon, so this is not the issue. Which "Preferences" do I need to check, the Preferences for the application or the System Preferences for Mac OS? Where do I unlock this protection? I've looked in the Mac OS System Preferences but I cannot find a way to unlock the protection. Any assistance would be appreciated. Thank you!