You can stop and remove the file transfer.

To stop and remove all transfers:

1. Right-click on the Transfer window and click "Remove All" from the Transfer window menu.

To stop and remove some transfers:

1. Select files of which you want to stop the transfer.
2. Right-click on the Transfer window, and click "Remove" from the Transfer window menu.

To delete finished transfers' logs:

1. Right-click on the Transfer window, and click Remove Finished from the Transfer window menu.