Found this problem as well, my main issue was that my client wanted to force the client to log back in without throwing them back to the AGOL/Portal sign in page.
What I found to work, instead of using just:
SessionManager.getInstance().signOut()
Which throws you out completely, you can clear the sessions, localStorage and sessionStorage.
SessionManager.getInstance().clearSessions()
localStorage.clear()
// or if you use localStorage and want to just replace the EB Auth info
localStorage.setItem('exb_auth','')
sessionStorage.clear()
After that you can refresh the page and the user will be forced to sign back in,
I also tried but unfortunately failed to simply de-authorize the current userSession or to force it to refresh with a new token that will expire when you want it to.