From your phone open up the call log (or phone) icon, scroll to the first entry you want to delete, then hold down the shift key and scroll to the other end of the list of the calls you want to delete. Hit the delete key and click to delete (or cancel if you didn't quite capture all the records you wanted). Hope this helps!
I've spent a few minutes trying replicate what the OP wants to do - delete all his OUTGOING calls in one operation- and haven't found a way to exactly that.
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However, you can easily delete all your incoming and outgoing calls together if that will work for you. In Messages, click Alt-P together (or MenuKey > View Folder > Phone Call Logs). Then scroll to the top phone log message, click MenuKey -> Delete Prior.
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