I have a PC that, over about 2 years, had about 3 scanners connected to it.
So now, when I want to scan, I get a dialog box, asking me to select which twain device to use.
I decided to do something about it and find out how to remove the old twain devices.
The solution is fairly simple: all twain devices are located in c:windowstwain_32
So I just create folder c:windowstwain_32_old
then I move folders (one at a time) to the _old folder, until I find the folder that is used for my current scanner. I then move the folder back, and move all the other files and folders from twain_32 to twain_32_old.
Remember to restart your scanning software after each move, so you can check which twain device you moved.
In my case, I went from 5 twain devices to 2… but I still cannot remove the “wia-HP scanjet2400 1.0 (32-32)” device… it looks like its tied to the “HP Scanjet 2400 TWAIN 1.0 (32-32)” device.