The rule I posted above is for the same purpose, it can replace your Disable action to a Delete. Modify the snippet to set Delete op when op is Disable.
for ( AccountRequest accountRequest : plan.getAccountRequests() ) {
if ( accountRequest.getOp().equals( ProvisioningPlan.ObjectOperation.Disable ) ) {
accountRequest.setOp( ProvisioningPlan.ObjectOperation.Delete);
}