How to fix "signatures do not match previously installed version" error?

Question

First, I have already uninstalled this app from my Huawei tablet device.

Now, I want to reinstall the APK with same package name using adb command line from my Mac.

./adb install ~/myapp.apk

I got this error:

Performing Streamed Install
adb: failed to install myapp.apk: Failure [INSTALL_FAILED_UPDATE_INCOMPATIBLE: Package com.example.myapp signatures do not match previously installed version; ignoring!]

From browsing around, I learn that perhaps the app did not uninstalled correctly. So I use adb shell.

$./adb shell

Device:/$ pm uninstall com.example.myapp
Failure [DELETE_FAILED_INTERNAL_ERROR]

Device:/$ pm uninstall --user 0 com.example.myapp
Failure [not installed for 0]

Device:/$ pm list package | grep myapp
(empty result)

Device:/$ pm list package | grep google
package:com.google.android.inputmethod.latin // which means list package & grep working fine

Device:/$ pm list package -u | grep myapp
package:com.example.myapp // which means pm already acknowledge myapp is uninstalled

So at this moment, I'm at loss. Even adb shell cannot see the app package. But still, when I try to install the APK, I get the error above. How can I resolve this?