I have a bunch of large files in my owncloud folder both locally on my OSX machine, and on my owncloud server. There is no need for these files to be kept locally as they are accessed only infrequently. Any time I delete a local copy of a file, it's also nuked on the server.
Is there a way to delete the local copy, but keep the server copy?
Quoting from the documentation of the sync client [1]:
The process of synchronization keeps files in two separate repositories the same. When synchronized:
If a file is added to one repository it is copied to the other synchronized repository.
When a file is changed in one repository, the change is propagated to any other synchronized repository.
If a file is deleted in one repository, it is deleted in any other.
If you want to achieve what you're looking for you can't use the desktop sync client and need to switch to a 3rdparty WebDAV client and access the files like explained in [2].
If you have the ownCloud app installed on Windows, you can right click on a file or folder under the ownCould hierarchy and select “free up space.” The file will remain on the server but the local copy will be deleted.