iPadOS by default will remove users when the number of cached users or reserved storage space per user is exceeded. iPadOS will delete the oldest cached accounts to allow space for new users to sign in. For more information, see Prepare Shared iPad in Apple Platform Deployment.
You can use Jamf Pro to view the user who is currently logged in to a Shared iPad device. If you need to remove a user from a Shared iPad device, you must manually delete the user in Jamf Pro. Shared iPad users may need to be manually deleted under certain circumstances. For example, you cannot upgrade a Shared iPad to iPadOS 17 if existing user accounts are present on the device. For more information, see the Upgrade a Shared iPad to iPadOS 17 Apple Support documentation. If you need to delete all Shared iPad users, you can use the Jamf Pro API.