Use the standard comment characters. [Edit: I see you wanted to comment out the Adapters node] For example, if you want to comment out the 'Adapters' node,
<Main>
<Services>
<Service name="01">
<Uses>
<Use type="front">
<Member name="01"/>
</Use>
</Uses>
</Service>
</Services>
<Adaptors>
</Adaptors>
</Main>