I think that the biggest example out there is that only phones are for having conversations. This idea has been completely 'unlearned' in almost anyones mind. Today, there are so many different ways of communicating with people that phones sometimes are on the bottom of the list. Twitter, Facebook, Instant Messaging, Text Messaging and even video chatting allow people to connect with one another almost anywhere and at the touch of a button. Along with this is the way that news is delivered. Instead of watching TV for the 5 o'clock news, people can quickly log online and search for any news that they want.
Another thing that I have had to 'unlearn' is using technology during school. In middle school, we all learned the dewey decimal system. Although I never fully grasped the system anyways, it really is unnecessary to know anymore. By looking on the computer you can find almost any resource you need.