You need to disable the user account. To do so, you need to follow the following steps:

1.    Admin will log-in and go to the option of “Users”.

2.    Once you click on Users, search for the user who resigned.  After getting the resigned users account, click on the user name and it will take you to the user account.

3.    You will find an option of “Edit User”.

4.    Click on “Edit User” and you will get an option of “Disable Account”. Check the box and click on “Save Changes”.