At the moment, the only way to delete a specific hand is to find it in your hand history folder, completely delete it and then reset your database (in SharkScope Desktop’s menu -> File -> Reset Database).
WARNING: resetting the database means that SharkScope Desktop will empty your database and repopulate it using the hand history files that are still on your computer. So it might happen sometimes that after resetting your database you see fewer hands than what you had initially. That is because some poker rooms (such as ACR) periodically delete some of those files from your computer without notifying you. For this reason, we highly recommend that you regularly keep a backup copy of your hand history folders.