Unable to delete archives in Standby db with rman

RMAN-08137: warning: archived log not deleted Error while deleting archive after backup using below command 

backup archivelog all format '/backup/$ORACLE_SID/arch/arch_flashblade_%d_%t_%s_%p' DELETE INPUT FILESPERSET 1;

Error:

piece handle=/backup/proddb01/arch/arch_flashblade_proddb0_1089597818_9469_1 tag=TAG20211126T020225 comment=NONE

channel c2: backup set complete, elapsed time: 00:00:51

channel c2: deleting archived log(s)

RMAN-08137: warning: archived log not deleted, needed for standby or upstream capture process

archived log file name=/san/proddb0_fra/1_7456_1085402700.arc thread=1 sequence=7456

Cause:

log_archive_dest_2 on standby which points to primary database was deferred

SQL> show parameter dest_2

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

db_create_online_log_dest_2          string

log_archive_dest_2                   string      SERVICE=proddb01 LGWR ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=proddb01

SQL> show parameter log_archive_dest_state_2

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

log_archive_dest_state_2             string      DEFER

log_archive_dest_state_20            string      enable

log_archive_dest_state_21            string      enable

log_archive_dest_state_22            string      enable

log_archive_dest_state_23            string      enable

log_archive_dest_state_24            string      enable

log_archive_dest_state_25            string      enable

log_archive_dest_state_26            string      enable

log_archive_dest_state_27            string      enable

log_archive_dest_state_28            string      enable

log_archive_dest_state_29            string      enable

Solution:

set null values to dest_2 and enable dest_state_2

SQL> alter system set log_archive_dest_2='' scope=both sid='*';

System altered.

SQL> alter system set log_archive_dest_state_2=enable scope=both sid='*';

System altered.