If you have AAA services configured on your Cisco device and want to do some, for example, EEM remote telnet on that device you will have problem with executing commands because of AAA services. Because of that Cisco introduced useful command annex to classic EEM - authorization bypass. Be sure that your IOS version support that...
Here is one example of configuring EEM with AAA on device for remote telnet and do some clear ARP for you:
event manager applet chilly authorization bypass
action 2.0 cli command "telnet x.x.x.x" pattern "Username:"
action 3.0 cli command "admin" pattern "Password:"
action 4.0 cli command "password" pattern "#"
action 5.0 cli command "clear arp" pattern "#"
action 6.0 cli command "exit"
action 7.0 cli command "end"
That was another post about EEM...keep playing with this powerful tool...