Remove unused API

Bug: 20303449
Change-Id: I7101a9fdf548bf1828e3a427dcbb63f6376b6573
diff --git a/system-api/23.txt b/system-api/23.txt
index 8fba945..1c9e7bd 100644
--- a/system-api/23.txt
+++ b/system-api/23.txt
@@ -30232,7 +30232,6 @@
     method public android.telecom.PhoneAccount getPhoneAccount(android.telecom.PhoneAccountHandle);
     method public java.util.List<android.telecom.PhoneAccountHandle> getPhoneAccountsForPackage();
     method public java.util.List<android.telecom.PhoneAccountHandle> getPhoneAccountsSupportingScheme(java.lang.String);
-    method public java.util.List<android.telecom.PhoneAccountHandle> getRegisteredConnectionManagers();
     method public java.lang.String getVoiceMailNumber(android.telecom.PhoneAccountHandle);
     method public boolean handleMmi(java.lang.String);
     method public boolean handleMmi(java.lang.String, android.telecom.PhoneAccountHandle);