You can use the No Further Action (NFA) functions for pupils so that you don't delete them and keep your information.
Check the services
When you mark as NFA, their record colour only changes when the pupil is marked as NFA against all the services they're attached to. If you expect a colour change and don't see it, it's likely this issue.
To check their information, follow these simple steps.
Click Security Manager, then click Users.
Click Services.
Here you can check the assigned security services and if you need to, mark NFA against the outstanding service.
Colour only shows for some users
If you're seeing that the could is only changing for some users, it's down to the services that specific user has access to.
For the colour change to happen, you need to mark all services the user has access to.
For example, if a user has both SEN and FSMB services under their user, the pupil needs both services marked for a colour change. If another user only has SEN, they only need that marked for the colour change.