Whenever you are deleting a user, the system requires that you remove him/her from escalations and schedules. This is to ensure someone is on-call during the deleted user’s shifts.
Depending on where the user is located in the ‘list of participants’ in the Rotation Settings, the future on-call schedule will be modified upon removal. There are two options here:
1.) If you don’t want anyone on-call during those times, you can simply add the dummy user “No-One” to the exact place in the participant order, from where you are removing the user.
2.) If you do want someone on-call during those periods (I believe you do), instead of removing the user, you can replace her with someone else. That way, for the rest of the participants, the future on-call rotations stay the same.
An on-call schedule is rotating a predefined set of participants based on a custom logic - removal will always impact the future on-call shifts. Otherwise, there would be gaps.
Does this help?