As Al Everett pointed out there are a few ways to remove an unofficial app from Android. In fact uninstalling an app was simplified with Jelly Bean. I will cover two ways of uninstalling an app, both of which were mentioned by Al Everett.
The first (and arguably easiest way) is to open the app drawer, normally represented by a grid of squares that can be surrounded by a circle. Next you want to tap+hold your finger on the app you wish to remove. After a brief moment you should see a trashcan either at the top or at the bottom of your screen, drag the app to the trashcan and let go. At this point you should be prompted by Android to verify the app uninstall. Go ahead and confirm that you want to remove it.
The second way involves going into the device settings, which in itself varies depending on device and version of android. Lets go with the easiest way in Jelly Bean.
Tap your finger on the top edge of the screen and drag it down. This opens your Notification panel. On the panel should be an icon in the top right corner that looks like a stick figure portrait with little boxes along the right and bottom edges. Tap this to switch to a secondary panel that should have your "Settings" option. The Settings icon looks like horizontal slides with the word Settings underneath them.
Once you are in the setting menu scroll down until you see "Apps" and tap on it. Now scroll down until you find the app you want to remove and tap it. You should now be on a new screen that provides some information about the app, and contains a few buttons. The main thing we are interested in on this screen is the "Uninstall" button, this does exactly what it says and will remove the app.
Here is where I will provide some personal advice, before you uninstall the app I would decide if you will be installing it again any time soon. If you are not then I recommend tapping the "Clear Data" button before you remove the app. I have had a few rare occasions where the app data was not removed properly when I removed an app and I was unable to re-use that bit of storage on my phone, but again, this has been a rare issue for me.
There you have it, 2 detailed ways to remove an unofficial app (well, any non-system app really) from Android.