I usually initialize some objects:

Dim swApp as SldWorks.SldWorks

Dim swModel as SldWorks.ModelDoc2

Dim swPart as SldWorks.PartDoc

set swApp=Application.SldWorks

set swModel=swApp.ActiveDoc

set swPart =swModel as SldWorks.PartDoc

When Macro finish, I destroy these objects.

set swApp=nothing

set swModel=nothing

set swPart=nothing

If I only destroy swApp object, can swModel and swPart  release resource?

set swApp=nothing