Please follow the instruction how to move it:

1. Create a new Part.
2. Add coordinate system.
3. Find an existing part whose origin is centered in the assembly.
4. Fix the components together.
5. Create a coincidence constraint between the two axes systems.

To see step by step how to do it, please check the document below.

 Moving an Assembly

See also: How to move a Part while preserving the same coordinates system?