A dependency means the driver object is still being used some place else in your process file, i.e., another object or expression is refereing to the object or a datamember within the object. I will assume you have the newest version of Lookout. If so, go into edit mode and click on the "Object" item in the menu at the top of the Lookout window. In that menu there is an item called "Connection Browser." This will show you the inputs and outputs of any object in you process file.
You will. in all likelyhood, find an output of the driver object in question. Once all outputs (by editing the appropriate objects) are removed you will be able to delete the the driver object.
Regards,
Tommy Scharmann