OK, Paul, let's start with your telling which Model TomTom you use.
First off, the items you list as POIs are actually the Safety cameras for those countries of which I gave you the Internet two letter designations, not Points of Interest.
I trust that you made a complete back up of your device with Windows Explorer,
not HOME.
After you did that, connect with HOME and select Manage my GO (your device).
Here in Manage your navigation device are two columns. One shows what is actually at this moment on your device, the other what is on your computer (including the full path to the folder in which it is).
The question now is "Why do you want to delete anything?"
If you need the space (this is why I asked which TomTom you have), short of your Application (Operating System) and map you could delete anything as you can copy it back any time from your complete back up folder on your computer.
In the screen print below you will see that I have 18 car symbols on my device. I only use the default blue arrow head. I didn't bother to delete anything as I still have 3.6 GB free space between the internal memory and the SD card.
What exactly are you trying to do with you device. How do you want to use it. Do you need the space to play music?
Manage_my_GO.jpg