How to clear SM/AWR old snapshots if sysaux show it having large usage.

In the article Note:  387914.1 WRH$_ACTIVE_SESSION_HISTORY Does Not Get Purged
In show that require to split the partition

alter table WRH$_SQLSTAT split partition WRH$_SQLSTA_2446360981_11691 at (2446360981,12774)
into (partition WRH$_SQLSTA_2446 360981_11691 tablespace SYSAUX, partition WRH$_SQLSTA_2446360981_12774 tablespace SYSAUX)
update indexes;

so, i wonder why it require to split the "WRH$_SQLSTAT" instead of "WRH$_ACTIVE_SESSION_HISTORY"?   <-- question 1

my situations are as below...


02:37:25 SQL> SELECT * FROM V$VERSION;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production
PL/SQL Release 11.1.0.7.0 - Production
CORE    11.1.0.7.0      Production
TNS for Linux: Version 11.1.0.7.0 - Production
NLSRTL Version 11.1.0.7.0 - Production

02:38:20 SQL> select SPACE_USAGE_KBYTES/1024 "AWR Size [MBytes]"      from V$SYSAUX_OCCUPANTS