You can remove the snmp community using the web interface available on the 9300.
In order to access the web interface you need a snmp community, since you dont remember yours simply add a new one.
"snmp-server commmunity <STRING> rw"
after this open a web connection to your switch, the user is "set" and the password the string you selected before.
From the main screen select
-> management
and then
-> comunity string
You will see the community you just added and the one you had before, you will also have the option to delete any of the two (if you delete the one you used to log on to the web the switch will disconnect you).
Hope this helps
Regards
Guillermo</STRING>