Remove unused file

It got split apart to actually work at some point, but apparently nobody
remembered to remove the old combined one.

Change-Id: I4fa6e82ccdf28ded1bc553aa158ef4fe22fe2857
diff --git a/aos/events/pingpong.fbs b/aos/events/pingpong.fbs
deleted file mode 100644
index 67e5015..0000000
--- a/aos/events/pingpong.fbs
+++ /dev/null
@@ -1,14 +0,0 @@
-namespace aos.examples;
-
-table Ping {
-  value:int;
-  send_time:long;
-}
-
-table Pong {
-  value:int;
-  initial_send_time:long;
-}
-
-root_type Ping;
-root_type Pong;