thank you for the detail explanation.
I tested in vmware, with fresh installed windows 10.
MC version is "MultiCommander_x64_Portable_(12.0.0.2903).zip"
it is not likely AV software or column locking the folder, because
it can delete c:\folder1 from the left panel when:
left panel is c:\
right panel is c:\folder1
it can not delete c:\folder1 from the left panel when:
left panel is c:\
right panel is c:\folder1\folder2
all the folder have no files, only empty sub-folders.