5 Steps to uninstall freenet in windows:

Now Open start-menu and go to Run, 
in there you type: cmd

Quick: Win+R

In there you need to Change directory to 
the folder of freenet.

Common Folders: 
         C:\Program\Freenet\
         C:\Program\Files\Freenet\
       C:\Freenet\

Make sure the service is not running by 
typing stop.cmd

Why: 
To stop the service.

Now when you are in the Freenet Folder in 
the CMD window you need to type:
bin\wrapper-windows-x86-32.exe -r ..\wrapper.conf

Why: 
To remove the windows service.

Now you can just simply select the freenet folder and 
delete it and freenet is uninstalled