I downloaded the latest version of Safari and I am still on OS 10.7.5. How do I uninstall this version of Safari and install the latest version for my OS?

The only way to update Safari to a newer version is to upgrade your Mac. If you upgrade to v10.11 El Capitan, that will update Safari to version 9.0.1 which is the latest available.

El Capitan v10.11 requirements:

• iMac (Mid-2007 or newer)
• MacBook (13-inch Aluminum, Late 2008), (13-inch, Early 2009 or newer)
• MacBook Pro (13-inch, Mid-2009 or newer), (15-inch, Mid / Late 2007 or newer), (17-inch, Late 2007 or newer)
• MacBook Air (Late 2008 or newer)
• Mac Mini (Early 2009 or newer)
• Mac Pro (Early 2008 or newer)

El Capitan is available for download for free at the App Store. If you decide to upgrade, make sure to backup all your important data beforehand.

If you are running OS X 10.7.5, the last version of Safari was Safari 6.1.6

You would need to upgrade your Mac to a later version of OS X if you need a later version of Safari.

If you can no longer use Safari 6.1.6 and you either can not or do not want to upgrade your OS X, another alternative would be to download and install Firefox. The current version of Firefox is still supported for OS X 10.7.5

Firefox