One of the advantages of applying different launchers is to get a whole new user experience. To switch launchers on Android and change the current default launcher, you are going to have to do as follows:
1. Open Settings and go to Apps (Note that on some Android device it is App Manager, and on some Android devices like Galaxy S4 you may have to change tabs)
2. Find the name of the current launcher, already set as default, and open it (For example if you are now using Nova Launcher as your launcher, you need to find Nova and then tap to open it)
3. Scroll down, and tap the "Clear Defaults" button
4. Now press Home Button to go to home screen
5. A popup menu is shown, and asks you to select the Launcher
6. Select the Launcher from the list, and tap Always to set it as the Default Launcher
7. You managed to switch launcher :)
If you are running Android 4.4 KitKat, you simply need to go to Settings and select Home and then easily change and Switch launchers on Android.
On some LG devices, like Optimus G, there is another easy way to switch launchers. Read: How to Switch Launchers on LG Optimus G