Hi Cassie,
We have a agood document on Meet me conferencing here:
https://www.myciscocommunity.com/docs/DOC-1518
With regards to your question, meet-me doesn't allow the conference admin to mute a specific participant. They can mute themselves by either hitting a mute button on their phone, or by dialing the "mute-on" number configured under telephony-service.
Thanks,
Marcos Hernandez
Technical Marketing Engineer
Cisco Systems, Inc.