Option1:If you want to wipe out the data from the module then the best way is to create a line item formatted as No data and Import this line item into a line item which contains data. This will remove the data from the line item and make it zero
Option2: Another way is to select the “clear target prior to import” within an import action. But this has a caveat which means that the number of items loaded earlier has to be exactly the same when you try to load it with zeros..
Agree with @Misbah - best way is through an action. If you want an immediate delete and are okay doing it manually, you can just change the formula of the line item you want to delete to blank or 0, then remove the formula. If you are attempting to delete a delta load, that's much trickier. For that you need to have a Boolean that identifies which list item was changed. Some people use this method, which I believe is considered best practice. I sometimes just load a line item that contains a time stamp then use the MAX function to determine the last load. If the list item matches the last load timestamp then I know it's a delta.