I'm developing application using Autodesk Forge API. I want to implement sign out not only from my app(by session cleaning) and from Autodesk Account.
There is no such thing as sign out because what your App performs is not a sign in ... What it does is - I assume you are talking about the 3-legged Forge OAuth API - asking the user to authorize a specific App (set of API keys) to access user data on the Autodesk Cloud (A360). Once an App has been authorized, it could keep refreshing the token undefinitely. What Forge is missing at the moment is an admin console for the user that would list authorized Apps and provide a way to unauthorize any of those Apps. It's not there yet unfortunately.