In order to manipulate the grade book grades for a withdrawn student you will need to re-enroll the student in the school.
  1. Navigate to Core > Users > Edit User Profile Data
  2. Search for the withdrawn Student
  3. Scroll down to the System Information section and click Student Enrollment
  4. Click Re-Enroll
  5. Mark the first option Re-enroll into school year (the current year)
  6. Save & Exit
Now that the student is enrolled in school again, you will need to re-enroll them in the course.
  1. Find the course using the Group Finder in Academics
  2. On the Roster tab select the Term for which the student needs to be enrolled
  3. Click Manage Roster
  4. Add the student back into the roster
This will put the student back into the grade book. Once they are in the grade book you can add or edit the assignment grades as needed.

Once all of the corrections to the grades are complete, its time to withdraw the student again.
  1. Navigate to Core > Users > Edit User Profile Data
  2. Search for the Student
  3. Scroll down to the System Information section and click Student Enrollment
  4. Click Withdraw
  5. Mark "Effective Immediately"
  6. Select the school year from which the student is being withdrawn
  7. Enter the Depart Date (Can be anywhere in the past within the school year selected)
  8. Mark Past Student for the role
  9. Save & Exit