There shouldn't be any locks for the tpks files. Could you describe the use case more in detail? Are you using the file in a map at the same time? Have you removed all the references to it's usage? Are you just deleting the file?
Any layer that currently renders the layer will keep a read lock on the TPK. Make sure all objects that references the TPK are released and garbage collected, and then you should be able to delete it (you might have to wait for GC to complete first)