Only Pobble admins can make changes to your team page. It may be that they have left school and did not re-assign the role. Don't worry though, we can do this for you.
That person will then be able to reassign this role to others (if they wish) by clicking their account icon in the header, clicking 'School settings' and then 'Team'. Members of your team can be added or removed as Admin by clicking the action button (the three dots '...') and making the selection to "Promote as school leader".