2
The same way as you've installed them - through the Admin.
1) Go to Modules listing, un-check the "Active" checkbox next to you module that you want to unistall, and click on "Submit" button
2) Confirm on the next screen
3) You'll back to the Modules view, but now you'll have an extra new icon with a "black disk image" next to your module.
4) Click on it, and this will uninstall you module