To manually remove an app, you'll need to (manually) delete all of the following items:
- The app's package, usually in
/data/app/<package name>. For system apps, delete
/vendor/app/<something> instead, depending on where it resides. The folder and file name are not necessarily the same as package name for system/vendor apps, though.
- The app's installation information,
/data/system/packages.xml. This is very complicated as an app may define resources that can be used by other apps. Be sure to remove all related keys and leave unrelated keys intact, or you can mess the files up.
Additionally, these items may be removed, but they'll be pruned if some or all items listed above are manually removed or found missing. The automatic pruning usually happens during system booting.
- The app's Dalvik cache, in
- The app's data, in
- The app's data in external storage, in
- The app's "simplified information" in
/data/system/packages.list, which will be pruned if the app is gone from
Sometimes you'll see some log in
/data/system/uid_error.log if the above items are pruned by Android.