Hello
To do it in CLI:
(config)#icmp permit 0.0.0.0 0.0.0.0 outside
To do it in ASDM:
Configuration => device management (left pane) => Management Access => ICMP.
Click ADD, select outside interface, "echo" in ICMP type and "any address" (except if you want to be more specific considering the IP that will have the possiblity to ping ASA on outside interface), choose PERMIT as the action.
Apply changes and test with a ping from the outside.
Hope it will help you
Francois
