Hi,
I am assuming you just want to remove the dial soft key. This can be removed by editing the softkey template used by the Phone in different state's but if you dial the number and lift the handset, phone would still dial the number.
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/7_1_2/ccmcfg/bccm-712-cm/b06skey.html
If your purpose is to disable the dialing from the phone than you need to make sure all the dial able numbers/DN's are in a partition and the phone does not have any CSS applied on the line or the phone level.
