To change an enrolment status go to; Admin> Students> Group Updater
Choose the student's year and form from the drop downs and select "Enrol Status" for the Student Attribute drop down. Click "Choose."
Tick the select box next to the relevant students name
From the dropdown above the table choose the new enrol status you wish to apply to that student.
Click on Update Students at the bottom of the page, and the enrol status will have changed for them.