How do I really delete an imported module?

[Robin Becker]

....well you have to delete all references to the module before it goes
away. There are references to re in other library modules, but I suspect
that most of re is in an extension (or built in). I believe that
extension modules are not normally unloaded.

Even so, for a python module, I think it depends on the OS whether
you'll see a decrease in vmem (and perhaps the allocation/deallocation
order). 
-- 
Robin Becker