Well,
I don't know what happened yesterday.
Also exiting from b4j and restarting it, in debugging mode and also in release mode, the delete instruction was always False
But with explorer , with the app closed, I could delete the fiie. Of course, with the app opened, I coudn't do it. Permissions were OK.
Today, after the restart of the PC 'file.delete' works correctly.
Then it seems that one istance of raf.initialize remains attached.
The same, it is strange for me that yesterday with explorer I could delete the file and with code I didn't.
Probably an occasional event that I don't understand. To be sure, I'll release the app to the user writing an empty list instead of deleting file.