commands: fix unused-function warning

Change-Id: I3227a7245ebb8eede99b5469f3aa0cffaafe9450
Reviewed-on: https://weave-review.googlesource.com/1732
Reviewed-by: Alex Vakulenko <avakulenko@google.com>

src/commands/command_instance.cc

diff --git a/src/commands/command_instance.cc b/src/commands/command_instance.cc
index c6a9600..1f2e4a2 100644
--- a/src/commands/command_instance.cc
+++ b/src/commands/command_instance.cc
@@ -35,13 +35,6 @@
     {Command::Origin::kCloud, "cloud"},
 };
 
-bool ReportDestroyedError(ErrorPtr* error) {
-  Error::AddTo(error, FROM_HERE, errors::commands::kDomain,
-               errors::commands::kCommandDestroyed,
-               "Command has been destroyed");
-  return false;
-}
-
 bool ReportInvalidStateTransition(ErrorPtr* error,
                                   Command::State from,
                                   Command::State to) {