To Sign Out from all Apps, click on the Profile link in the top right corner. You will see a drop down with an option to Sign out. Signing out will close all your other open applications in other tabs in the active browser.
Closing the account will close the account and terminate access to all the applications. You will not have access to any applications. Only personal users will be able to close their accounts.
Only the admin can delete the organization users accounts.
In case you have hosted your domain with mail or have an active subscription, you need to cancel your subscription, delete the domain, delete the organization and then close the account.
In case you have set up an organization account, and want to change your account to a personal account, or want to join another organizations account, you have to delete the current organization in which you have Super Admin role, before joining the other organization.
The three major steps before you delete the organization are removing users, deleting domains and cancelling any paid subscriptions you are part of.
You need to remove all the domains mapped under your organization, before you delete the organization.
The domains registered through the application, cannot be deleted from Domains section.