In situations where you want to deactivate but not delete a user, you have an option to make such a user inactive. Doing that gives you a chance to reactivate the user at any desired time, such as when the user is back from leave.
Disabling a user account
To make a user account on your team inactive:
Tap the avatar image, then click Manage your organization
Navigate to the desired user and click the pen-like edit icon
Toggle the Active user button to the off position, then click Update