You can use the bunny killer to remove any Unity properties they might have in AD, but other than that, CUC/CUCM won't mess with the AD itself so, assuming you already have all the VM profiles, call handlers, AA, etc pointing to CUC you can safely turn it down and delete any remaining Unity configs from CUCM (if any are left).
No real need to uninstall Unity, you can just power it off.
HTH
java
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www.cisco.com/go/pdihelpdesk
HTH
java
if this helps, please rate