Sharepoint - Cannot delete document, error: The file is currently checked out or locked for editing by another user

If you examine the item using PowerShell you can get a better idea of what is going on. In all the cases where I have seen it the lock expires after short period(20 minutes) and has been caused by word setting a lock when a user has selected to edit the file:

$web = Get-SpWeb http://somesite.net
$item = $web.GetListItem("/relative/url/to/item.doc")
$item.file.LockType
$item.file.LockedByUser
$item.file.LockExpires

If you are facing this error while deleting empty folder "The file is currently checked out or locked for editing by another user.", Then it might be because of there are documents in the library that don't have a major version published.

Yo can go into the Library Settings and take ownership of the files. Then delete the entries, and the folder can be deleted.

Library Tools > Library > Library Settings > Permissions and Management > Manage files which have no checked in version