If you want to disable the esxi firewall service for some reason, you can disable it with the command below.
esxcli network firewall set --enabled false
Note that when you stop this service, esxi services are opened to the outside world. so re-enable it after making the necessary changes.
Running the below steps listed at the above link allowed me to start SNMPD in the EXSi GUI without issue
esxcli system snmp set -r esxcli system snmp set -c YOUR_STRING esxcli system snmp set -p 161 esxcli system snmp set -L "City, State, Country" esxcli system snmp set -C noc@example.com esxcli system snmp set -e yes