To improve security, you can clear passwords and user accounts from the sign-in window. Clearing passwords and user accounts is especially important if you sign in from a public computer, or if multiple people use the same computer.
When you clear user accounts, user IDs, passwords, and display names are deleted. Contacts are not deleted from accounts.
Close any conversation windows.
If you are already signed into Lync, on the Status menu, click Sign Out.
On the Email address pop-up menu, click Clear all saved accounts.
Important: When you clear user accounts, saved conversations are not deleted from the Conversation History. To delete conversations from the Conversation History, sign in to your account, click on a contact, and then on the Contact menu, click View Past Conversations. Select the conversations that you want to delete, and then click Delete .