Below are the steps for creating password file for database in ASM diskgroup .

This method is valid only for oracle 12c onwards.

SYNTAX –

ASMCMD> pwcreate –dbuniquename {db_unique_name} {file_path}  {sys_password}

Example:

Here we will create a password file with dbuniquename PRDPRE.

ASMCMD> pwcreate --dbuniquename PRDPRE +DATA/PWDFILE/pwdPRDPRE oracle

Check whether new pwdfile is created or not:

ASMCMD> pwget --dbuniquename PRDPRE
+DATA/PWDFILE/pwdPRDPRE

We can check the database config using srvctl also:

srvctl config database -d PRDPRE


Database unique name: PRDPRE
Database name: PRDPRE
Oracle home: /oracle/app/oracle/product/12.1.0.2/dbhome_1
Oracle user: oracle
Spfile: +DATA/PRDPRE/PARAMETERFILE/spfile.269.943055251
Password file: +DATA/PWDFILE/pwdPRDPRE            --------->>>>>>>>>>>>>>>>>> password file location 
Domain:
Start options: open
Stop options: immediate
Database role: PRIMARY
Management policy: AUTOMATIC
Server pools:
Disk Groups: DATA,REDOA,REDOB
Mount point paths:
Services:
Type: RAC
Start concurrency:
Stop concurrency:
OSDBA group: dba
OSOPER group: dba
Database instances: PRDPRE1,PRDPRE2

Another alternative way to create password file inside asm diskgroup is:

orapwd file='+DATA/orapwPRODPRE' ENTRIES=10 DBUNIQUENAME='PRODPRE'