SBG3600: How to get back to standalone mode instead of Managed AP?

Hello

When I enter my homepage of device setup (SBG3600) I see a section "Service Status". It tells me that Status is "Enabled", Name is "Managed AP" and it has no Version nor Expiration values.

What is this and how I can disable it?

My firmware is V1.00(AAKO.9).

Thanks for response.