Technical Tip: How to delete a unused SSID on FortiGate

1. Remove all references to the SSID from the GUI.

• Go to Network → Interfaces and remove or change any interfaces that use the SSID / VAP.

• Remove related firewall policies (for example, under Policy & Objects → Firewall Policy) that reference this SSID interface.

• Verify that the SSID has no references. Delete any related Address objects, DHCP server entries, or other objects that still point to this SSID.

• If needed, see this article: Technical Tip: Unable to delete SSID for details on finding and removing all references from the GUI.

2. If the SSID still cannot be deleted and the CLI shows error ret=-160, use the config-file workaround: Technical Tip: How to download FortiGate configuration file & Debug log from GUI.

• Edit the configuration file offline.
• Open the config file in a text editor.
• Locate the config system interface section.
• Find the edit '<SSID-name>' entry that corresponds to the stuck SSID (for example, the VAP interface).
• Carefully remove only that interface block.
• Upload and restore the edited configuration to the FortiGate
• Confirm that the SSID interface no longer appears and that no other configuration items are missing.

Recommendation:

Use the config-file method only when the normal GUI reference-cleanup process does not allow the SSID to be deleted. Always keep a backup of the original configuration in case a rollback is required.

Another option is to remove the SSID via CLI when it is not possible to remove it from the GUI:

config wireless-controller vap
    delete "<ssid_name>"
end

Related article:

Technical Tip: Unable to delete SSID