The option to edit shifts in bulk is available to Premium and Business subscribers and will allow you to edit any and/or all shifts in view at once. This also applies to a shift's published status.
First, select the range of dates you wish to unpublish. You can also apply filters if you want to focus on a specific location, position, employee, etc.
Click the select all box, then click the edit icon.
A popup will appear where you can choose what info about the shifts you want to edit. Choose publish status from the first menu, then choose unpublish all from the second list.
Finally, click Save and all the selected shifts will be unpublished and removed from your employees' views.