The apps installed on your Android devices can be broadly categorized as system apps or user apps, based on their installation location. The user apps are just all your normal app installations through the Google Play Store, Amazon Appstore or sideloading. These go into the /data partition of your Android phone, which is the part of the internal memory made available for user data and apps.
System apps are basically the apps that come pre-installed with your ROM. In a standard Android user environment, the user doesn’t have write access to the /system partition and thus, installing or uninstalling system apps directly isn’t possible. The process isn’t as hard as it may sound. However, there is a catch.
In order to install an app as a system app on your Android device, your device must either be rooted, or have a custom recovery installed (or both). Usually pretty much everyone who has a custom recovery installed uses a rooted ROM, so we’ll just be using the method for rooted phones.
Go to below tutorial.it might help you.
Make Your app System App
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