Hi,
I tried this again with a fresh new browser, still the issue exists.
I have also deactivated and reactivated plugin, after that can’t able to view the settings page(“../wp-admin/options-general.php?page=wp-gotowebinar”) of the wp-gotowebinar in the admin login.
Info :
wp-gotowebinar(version : 8.3).
WordPress(version : 4.1.1).