Perfect. Thank you very much!
For everyone who wants to try that, I have now:
bat file:
Name: C:\Users<username>\AppData\Roaming\Mp3tag\delete wmp files.bat
Code:
cd %1
attrib -h -s *.* /s
del /s folder.jpg
del /s albumart*.jpg
del /s desktop.ini
Mp3tag tool:
Name: Delete WMP Albumart Files
Path: C:\Users<username>\AppData\Roaming\Mp3tag\delete wmp files.bat
Parameter: "%_path%"
\s stand for subfolders, right? I can leave that away to avoid accidental deletion of folder.jpg files form more folders if I accidentally executed the tool from a folder which holds different subfolders with different albums. Is that correct?