To give a colleague access to your CentralPlanner account, click on the cogwheel at the top right and select the Account settings. There, click on Add a user.
Always use this option and create different accounts, at least for different service areas (with shared logins if necessary). This is the only way you will later be able to track who has done what in the system and trace errors or prevent misuse.
The new user now receives an invite email, with a link to create a password. They then get access to this CentralPlanner account. You can then edit the user's rights and determine what can be changed.
To deactivate a user, click Manage or delete users in your Account settings. There you have options to edit their rights and to deactivate them. Deactivation means that this user no longer has any access to the account. Users are not completely deleted in CentralPlanner so that you can still trace their history later.