you can use the either the local or tacacs login for console line.
Router(config)#line console 0
Router(config-line)#login ?
local Local password checking
tacacs Use tacacs server for password checkin
for local, create a local user database
Router(config)#username privilege 15 password
for tacacs, you need AAA (local database for secondary authenticatio if tacacs doesn't work) and tacacs server host configured:
Router(config)#aaa new-model
Router(config)#aaa authentication login default group tacacs+ local
Router(config)#tacacs-server host
To disconnect or "kick" users, do a clear line and choose which connection to disconnect
Router#clear line ?
<0-6> Line number
async-queue Clear queued rotary async lines
aux Auxiliary line
console Primary terminal line
vty Virtual terminal
