That's not true. Of course can it be deactivated, but you have to do this manually in the registry at your own risk. If needed the service can be started manually by executing pdf24.exe.
Start regedit under a user with admin rights. For a backup export the whole registry.
The key can be found under
[HKEY_LOCAL_MACHINE/SOFTWARE/Wow6432Node/Microsoft/Windows/CurrentVersion/Run]
"PDFPrint"="E:\Application\PDF24\pdf24.exe"
Remove this value and the service will not be started the next time you boot your computer. The key can be reimported by creating a reg file (e.g. pdf24.reg) with the following content:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE/SOFTWARE/Wow6432Node/Microsoft/Windows/CurrentVersion/Run]
"PDFPrint"="E:\Application\PDF24\pdf24.exe"
and importing this file.
@pdf24: Why don't you guys tell that the users of your software? Most of the people here have enough knowledge to perform this simple action!