- defaults:
    name: global
    properties:
      - throttle:
          max-total: 2
          max-per-node: 1
          maxConcurrentPerNode: 1
          maxConcurrentTotal: 2
          throttleOption: project

Job template where throttle should be disabled:
    properties:
      - throttle:
          throttleEnabled: false

And what shows up in the config:
  <properties>
    <hudson.plugins.throttleconcurrents.ThrottleJobProperty>
      <maxConcurrentPerNode>0</maxConcurrentPerNode>
      <maxConcurrentTotal>0</maxConcurrentTotal>
      <throttleEnabled>true</throttleEnabled>
      <throttleOption/>
      <configVersion>1</configVersion>
    </hudson.plugins.throttleconcurrents.ThrottleJobProperty>