I don't use Win32::Gui, but in general, you don't destroy widgets to get rid of their data. Looking at the Win32::Gui tutorial, you may want Remove() instead of DestroyWindow. Maybe:
sub gitni_wchR_Deactivate {
print "Here\n";
####Win32::GUI::DestroyWindow($wchRW->wchR_lb0); #this is line n
Win32::GUI::Remove($wchRW->wchR_lb0);
}