SOAP Call question - remove a value?

I have several thousand Roles with direct Entitlement grants (oops) that
I would like to switch over to Resource's with Entitlement's instead.

So createResourceAssociation() no problem to link the Resource and the
Role. Got it.

Now to remove the Entitlement from the Role... Hmm, well there is no
direct function. If I were to try to add one, I would use modifyRole,
and there is an entitlement section in the SOAP.

This comes to a generic SOAP question. How do you say in SOAP, remove
one of a possibly multivalued set? Easy to specify add a value, never
quite clear on how to remove.

(IDM 4.5.2AE if it matters on Linux)