Follow these steps:
Select Network and Internet from the Start menu, then select Network and Sharing Center.
Choose Manage wireless networks from the task list.
Select the existing profiles in the Network table and click Remove.
If a caution dialogue box appears, simply click OK.
Then, under Network and Sharing Center, select Change adapter settings -> right-click Wireless Network Connection -> Connect/Disconnect.
To see accessible wireless networks, press the refresh button. Double-click or click the Connect button to connect to the network you want to connect to.