You can Re-Enroll the Student back into the dropped course (this is optional and is used only if you want to remove the course record completely and have no record of it whatsoever, if it doesn't matter then proceed to the To View/Remove Grades and Credits for a Student from a Course steps) .

To Re-Enroll the Student into the Dropped Course:

1) Navigate to onCampus.
2) Go to People > Academics > Course Roster.
3) Search the course and click Find.
4) Click Edit to the far right of the course. 
5) Click Add Member.
6) Search for the student, then click the double blue arrow icon to the left of their name to move them to Added Users.
7) Click Save & Exit.

To view/remove Grades and Credits for a student from a course:

1) Navigate to onRecord > Procedures > Grading > Manage Grades.
2) Use the Filter Options on the left to filter for the student, then click View.
3) To the right of Grades & Credits, or Grades & Credits - Dropped click View
4) Click Edit in the upper right corner.
5) Filter for the appropriate School Year, Group Type, Style and Course. (Don't forget to check to see if there are Assessment Style Grades and or Comments as those will also need to be removed from the Students Record)
6) Remove all associated Grades, Comments, and/or Credits. 
7) Click Save.

User-added image

You can then re-drop the student from the course, and select the "Scheduling Error" option. This will remove record of the course, and there will be no dropped course to display on the Report Card. 

User-added image