Upgrading to the latest version of the Small Package Quotes or LTL Freight Quotes extensions requires first removing the version currently installed. The settings entered into the currently installed version of the extension will not be lost as a result of this process. The settings will be retained and will automatically populate the newly installed version.
Login to the Magento Admin Panel.
Navigate to the Magento Connect Manager. (System > Magento Connect > Magento Connect Manager)
Login to the Magento Connect Manager using the same credentials you used to login to the Magento Admin Panel.
Navigate to the extension you want to remove and choose uninstall from the dropdown. Afterwards, click the Commit Changes button.
You'll be presented with a page similar to the image below if the uninstallation process was successful. Refer to the User's Guide for the latest version of the extension to perform its installation.