On mobile, you can restrict access to users by controlling the ability for your team to edit incident settings and invite team members.
All users will have full access as a default and by restricting access they will no longer be able to remove/add users or edit Incident settings.
Under the more screen you can, tap "Your team" to surface a list of your team members.
From here you can simply tap on the user that you wish to restrict access for.
Once you tap on the user that you wish to restrict access for you can then simply toggle to the right to restrict their access in Spotlight.