You cannot modify the "Assessment Released To" setting of a published assessment, but you can remove a published assessment, modify the settings in the pending assessment, and publish it again. To remove a published assessment, see Retracting or removing an assessment. To change the settings, see Assessment settings.
Note: Removing a published assessment deletes all student submissions and the corresponding gradebook item.
You can modify the settings, parts, and questions of any assessment listed under "Pending Assessments". When you publish an assessment, a copy is created and listed under "Published Assessments". For the published copy, you can make changes to all the settings except "Assessment Released To".
Note: After you've published an assessment, if you modify the unpublished version under "Pending Assessments", you'll have to alter the assessment's name before republishing it. When you publish it, you'll be creating another copy under "Published Assessments", not replacing the existing published copy.
Also, if you modify the settings of a test while students are taking it, the changes will not affect testing sessions in progress. Students must exit the test and re-enter it in order to have the modified settings take effect.