I am trying to remove the Facebook and Messenger apps from my Asus Zenphone Laser 2.
Unfortunately, in both cases, I seem to be unable to find the option to fully delete them from the device. I have disabled them, but the app management screen now shows the following:
How can I fully delete/uninstall them?
You can't remove those apps from firmware without root but you can uninstall any system app for current user or any user using ADB.
Assuming ADB is installed and PATH is set if not you can do it with a simple internet search.
Obtain package name for app you want to remove.
Open Terminal/Command Prompt
Make sure device is connected by running
adb devices -l
adb shell pm uninstall --user 0 <package name>
After some discussion in the comments I'm adding an example here that worked for me. I have uninstall Google Keyboard from my device for current user using command
adb shell pm uninstall --user 0 com.google.android.inputmethod.latin
Before and after uninstalling (click images to enlarge)
You cannot uninstall them as they are system apps. But if you can root your device then you can permanently uninstall them and all other bloatwares. You can root your device by installing Magisk (Magisk-XDA-portal) remember to read the post thoroughly before installing it!