When withdrawing a student who is not coming back next year, use a date outside of the School Year overall dates.

For example:
  1. From the menu in the upper left select Core
  2. Navigate to Settings > School Information > Years & Terms
  3. If 2018-2019 has a begin date of 9/1/2018 and an end date of 8/31/2019. You would use a withdraw date of 9/1/2019, this will keep the student's third trimester grades from dropping.