The configuration to hide the SSID could be seen under WLAN configuration.

Go to Configure > WLANs.
In the WLANs Section, select the SSID that has to be configured and click Edit.
In the Advanced options, in the Hide SSID Section, select or unselect Hide SSID option as per requirement and then click OK/Apply

If one has only a support info file, there's a way to find out through the RPM keys if the WLAN is hidden.
wlans/wlanx/wlan-ssid-hide='1'  --> SSID is hidden.
wlans/wlanx/wlan-ssid-hide='0'  --> SSID is broadcasting.

If the customer only has AP, we can access to AP GUI, do the following operation to unhide the SSID:
Go to Configuration > Radio 2.4G, find what you want to hide the SSID, click it.
In the Broadcast SSID Section, select Enable.
and then click Update Settings, You can find this SSID is broadcast.

We could also hide or unhide the SSID from the controller CLI using the below set of commands,

ruckus# config
ruckus(config)# wlan <WLAN name>
ruckus(config-wlan)# hide-ssid
The command was executed successfully.

We could use the "no hide-ssid" command so that the clients would see the SSID.