Well not really a total mess, but I tried out the windows 8 developer preview in parallels 7 and got my fix from that. I want to completely remove that virtual machine and any files associated with the windows 8 iso. I got my windows 8 dp from the microsoft site and just have the iso saved in my downloads folder. My guess would be delete the virtual machine associated with windows 8 and delete the iso file. Will that clear out everything or will I be leaving behind some files and junk that will just be taking up unnecessary space on my mbp?
You should be able to right click on the virtual machine in the virtual machine list and select remove. It will ask if you want to move the VM to the trash, which is just a single file, and you can delete the iso file.
I suggest you to check one more place: /User's Home Folder/ Applications (Parallels)/ If you can see "Windows 8" folder in there, you can remove and and free up some additional space.