NO. You'll not be able to update your app by changing target SDK from 23 to 22.
Users that have the APK with version code 6, which targets SDK 23 or higher, will receive an error when they attempt to upgrade to this APK because it targets SDK 22.
Now, as you all know, when we keep target SDK to <23, while installing the app by default all the permissions are granted for the app and if we keep target SDK 23 or higher, all the permissions are set to OFF while installing the app.
Ensure that your release including APKs targeting SDK 23 or higher to which all users that have the APK with version code 6 can upgrade.