Check In all Checked Out Documents

Check in all checked out documents by following this path in the custom report feature in All reports.

Run the Checked out documents report.
Select one, multiple, or all documents from the results.
Select from Quick Actions, and select the Version in the Options screen. Note: You can also Discard Checked Out to achieve the same result, but this is not recommended as it will delete any changes a user made to the checked out document.
Click
All your selected documents will now be checked in.