I had installed programs under WINE Tricks, which I removed again. Unfortunately the icons are still in the wingpanel. Where can I find the wingpanel menu file, so that i can delete the corresponding entries. I also want to add an entry manually (my special scanner program).
I think you're referring to "Desktop Entries". They are located in /usr/share/applications (for applications you install through the package manager) and in ~/.local/share/applications.
You can delete these with the filemanager. Open "Files" from the start menu. Then enter ~/.local/share/applications in the pathbar and hit enter. This should contain the corresponding files, but it doesn't show their title, just the filename. To check which is which you can open them in any text editor (right click -> Open with).
As for creating new entries, I'd like to refer you to this question on AskUbuntu.