Yeah if you want to get rid of parralels, drag parallels in the thrash and somewhere in the Documents folder, there should be your XP Virtual machine. Drag this in the thrash as well.
Or, you can install AppDelete and it will take care for you.
Since Parallels does more than just copying files to the /Applications folder the recommended way of removing Parallels from your Mac is by running the uninstaller program. You can find it in the disk image that you installed Parallels from.