Android studio - deploy the release apk instead of debug

Click the Build Variation tab on the far left side. If it is not there, press the monitor icon in the far left corner (the darker gray area):

In the build variation tab change from debug to release by clicking the list item.

On the left should be a "Build Variants" tab. There you can switch between your build types. If there no tabs visible than look left buttom for a monitor symbol and click it. Then you should find the build types. The selected one will be installed.