Log in as grid user or export to ORACLE ASM-HOME and SID as ASM instance if configured both grid and oracle in one user.
Method 1: Use alter user command.
Connecting to the ASM instance and executing an alter user
SQL> select * from v$pwfile_users;
USERNAME SYSDB SYSOP SYSAS
------------------------------ ----- ----- -----
SYS TRUE TRUE TRUE
ASMSNMP TRUE FALSE FALSE
SQL> ALTER USER asmsnmp IDENTIFIED BY <new_password>;
Method 2: Using orapwusr command.
Connect as grid user, and export ASM instance variables.
$ asmcmd
ASMCMD> lspwusr
Username sysdba sysoper sysasm
SYS TRUE TRUE TRUE
ASMSNMP TRUE FALSE FALSE
ASMCMD> lspwusr
Username sysdba sysoper sysasm
SYS TRUE TRUE TRUE
ASMSNMP TRUE FALSE FALSE
The username is case-sensitive while using orapwusr command, use ASMSNMP in upper case.
ASMCMD> orapwusr
usage: orapwusr { { { --add | --modify [--password] }[--privilege {sysasm|sysdba|sysoper} ] } | --delete } user
help: help orapwusr
ASMCMD> orapwusr --modify --password ASMSNMP
Enter password: *******
-- 12c and above.
ASMCMD> lspwusr
Username sysdba sysoper sysasm
SYS TRUE TRUE TRUE
CRSUSER__ASM_001 TRUE FALSE TRUE
ASMSNMP TRUE FALSE FALSE
usage: orapwusr {--add | --modify | --delete | --grant {sysasm|sysdba|sysoper} | --revoke {sysasm|sysdba|sysoper} } <user>
ASMCMD> orapwusr --modify ASMSNMP
Enter password: ********
ASMCMD>













