Don't know about a single step, that might be possible with iLogic or a macro or something.
Easiest manual method i can think of is:
- expand the "relationship" folder
- select the first constraint
- hold SHIFT and select the last constraint
- Hit DELETE (or right-click on a constraint and select "delete" from the menu)
Hope that helps
Niels van der Veer
Inventor professional user & 3DS Max enthusiast
Vault professional user/manager
The Netherlands