Android studio - deploy the release apk instead of debug

Solution 1:

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.

Solution 2:

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.

Solution 3:

Run a command

./gradlew assemble<variant_name>
//for example
./gradlew assembleRelease

[package aar]

After success build you can find .apk file at

project_path/app/build/outputs/apk/<variant_name>/
//for example
project_path/app/build/outputs/apk/release/

or just install via adb

adb install apk_path

Read more here