Error in deconfiguring AFD in 12c

Following the instruction at

https://docs.oracle.com/database/121/OSTMG/GUID-6AABD466-CC4D-4D17-92DB-42D65FB713F2.htm

to deconfigure Oracle ASM Filter Driver in an Oracle Grid Infrastructure Standalone (Oracle Restart) Environment

ORACLE_HOME and PATH have already been set.

# crsctl stop has <-- success

# acfsload stop  <-- no output; it probably means success

# asmcmd afd_deconfigure  <-- error

ASMCMD-9520: AFD is not 'Supported'

# crsctl stat res -t -init

...

ora.driver.afd

      1        ONLINE  ONLINE       dotridbms4               STABLE

At this point, I tried manually unloading oracleafd module:

# lsmod | grep afd

oracleafd             205543  0

# rmmod oracleafd

rmmod: ERROR: Module oracleafd is in use