Instant On - Wireless

I have a little problem about redirect the Instant ON SSID to the Fortigate Captive Portal. Such as I try to unset the password for Employee SSID, it won't let me yet done. So how can I unset the password or if it in the road map to unset the password to redirect to other portal before surfing the internet or using intranet either.

@ITC External captive portal is not supported on Instant ON. Please also note that we are constantly working to enhance the solution. Existing and future customers are going to get access to enhanced features and capabilities as part of future software updates. Firmware updates are automatically loaded on the APs and mobile app updates are made available in the iOS/Android app stores.