I doesn't really take a professional to do this rocket science --> http://lmgtfy.com/?q=deauth+specific+wireless+client
The first result:
www.aircrack-ng.org/doku.php?id=deauthentication
... MAC address of the client to deauthenticate; if this is omitted then all .... It is usually more effective to target a specific station using the -c parameter.


