How to delete the whole ASSEMBLY in ASSEMBLY Hierarchy ?

This question is annoying me for a time.

Hope someone to help me.

Poor English used, wish you can understand what I mean.

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In the ASSEMBLY Hierarchy, layed on the left plane of HYPERMESH.

For example,

I have two ASSEMBLY, named A and B.

ASSEMBLY A have three components, named aa, ab, ac;

ASSEMBLY B have two components, named bb, bc;

When I use mouse to right click on ASSEMBLY A, choose 'Delete',

ASSEMBLY A is deleted,

BUT, those components aa, ab, ac, which used to belong to ASSEMBLY A,

HAVE NOT BEEN deleted.

They go to the root, have the same level hierarchy with ASSEMBLY B.

Here my question,

How to delete ASSEMBLY INCLUDED all its assemblies and components in it with one Operation?

In this example,

I hope to delete ASSEMBLY A and those components aa, ab, ac at one time.