Once pass back is configured, any assessment that is Assigned on or after the start date will be passed back to Infinite Campus.
If you would like to remove a grade that was passed back from Otus to IC, you will first remove the grade from IC.
To prevent the grade from returning again during the nightly sync, you can toggle off "Include Score in Gradebook." This can be found by selecting "Edit" next to the assessment within the Assigned Assessment module.
If you would like to grade to appear in the gradebook at a later date, you can adjust the Due Date in the same Editing page.
A final option, is to un-assign the assessment in Otus. Please know that all associated student data will be removed when an assessment is un-assigned.