unalias -a
unalias AliasName ...
The unalias command removes the definition for each alias name specified, or removes all alias definitions if the -a flag is used. Alias definitions are removed from the current shell environment.
Since the unalias command affects the current shell execution environment, it is provided as a Korn shell or POSIX shell regular built-in command.
| -a | Removes all alias definitions from the current shell environment. | 
The following exit values are returned:
| 0 | Successful completion. | 
| >0 | One of the alias names specified did not represent a valid alias definition, or an error occurred. | 
| /usr/bin/ksh | Contains the Korn shell unalias built-in command. | 
| /usr/bin/unalias | Contains the unalias command. | 
The alias command, csh command, ksh command.