Is there a method for removing old/unused signatures in Outlook?
In DS-Manager there is no options to erase selectively or in bulk signatures from a client PC.
But this can be accomplished with a script.
Enclosed is a Powershell script that can determine the path to the signature folder and erase all signatures.
You should run this script prior to generating fresh signatures.
In a GPO you cannot be sure of the priority of execution, so you should use a method whereby you can ensure that it runs first. E.g. include a call to erase script and signature generation in a single bat or vb script of your own creation.