If you have accidentally assigned a large number of volunteers to a shift of a scheduled Activity (or an unscheduled Activity), you can easily remove them in bulk:
Go to: Assign >> From Scheduled List (or From Unscheduled List) in the sidebar menu
Select the desired filters to apply
Click the [+] in the header or to the left of an Activity to show all assigned volunteers
Check the boxes to the left of the volunteers you would like to remove from the schedule
Choose “Remove Selected Assignments” from the “Change Bulk Action” dropdown list.
Check the box to confirm
Click the [Remove] button
Note: Once a volunteer is removed from the schedule there will be no record of them ever being on the schedule/roster.