You need to uninstall it because you are using a different signature than the original. If it is not working it might be because it is still installed for another user on the device. To completely uninstall, go to Settings -> Apps -> (specific app)-> Options (the three dots on top right) -> Uninstall for all users.
I am also got this issue that time already installed ionic app(same package name) remove from my phone after that working perfectly.