The End Date of a Competency Assessment is the final day when Assessors can complete their assessments. When the Competency Assessment is in progress and the End Date is not yet in the past, the assessment cannot be closed. The Manager can add further assessors to the Competency Assessment in WX. As the HR Manager you can add and remove assessors, and change the Competency Assessment dates in HR Manager portal.
On the Close Date, the Close button appears to the Manager in WX. If the Policy option Auto-Complete Competency Assessment is enabled in your org, the Competency Assessment automatically closes and completes when all Assessors have completed their assessments. If a Competency Assessment has Assessors who have not completed their assessments at the Close Date or the Policy option is not enabled, the Manager needs to close the Competency Assessment manually in WX by selecting the Close button.