I already uninstalled the unwanted applications from my device, but they still show up on "Apps installed on" in my Google Play account. Does it mean that the apps I got rid of are still stored in my phone?
In the Play store there is a 'installed' tab which as the name implies is of currently installed applications. The 'all' tab shows apps which have ever been installed on the device.
If you don't want a application to show up in this list, then from the phone open Play store, go into your My Apps and on the All tab you can click the circular remove icon to the right of the app will remove it from your Play account.
I have a Motorola Moto G, with Android 4.4.4 installed on it, so your version might be slightly different.
On your device go to 'Google Play', and go to the 'Menu' (the 3 horizontal bars on the top left of the screen), the Menu should pop-up from the left side of the screen. Select 'My Apps' and a new screen should pop-up, the 'My Apps' screen.
On the top you will see two choices, 'installed' & 'all'. The first option is pretty self explanatory; the second choice lists ALL of the applications you have ever installed or uninstalled on your device. If you go down the list you will see that the apps are listed and neatly separated by little rectangles. Notice that the uninstalled apps have a little 'x' in the top right corner of the rectangle. Tap it and the device will ask you if you want to remove it from the list.
That is how you remove it from the device. It'll be removed from the Googe Play site when the phone syncs with Google's servers.