To get into the Netgear, if you don't know how already, try this.
https://kb.netgear.com/20026/How-do-I-change-the-admin-password-on-my-NETGEAR-router
This will help you turn off the SSID broadcasting or disable completely.
https://kb.netgear.com/23439/How-do-I-change-my-NETGEAR-router-s-WiFi-password-or-network-name-SSID
My recommendation would be to remove the Netgear completely. Secondary recommendation would we see if you can put the Netgear in "AP Only Mode" then connect it behind the MX along with the MR(Meraki AP), giving you better Wifi coverage.
Is there a specific reason you want to or need to leave the Netgear in the config?