delete unused pipelines
diff --git a/buildkite/pipelines/BUILD_file_generator-postsubmit.yml b/buildkite/pipelines/BUILD_file_generator-postsubmit.yml
deleted file mode 100644
index dd13f44..0000000
--- a/buildkite/pipelines/BUILD_file_generator-postsubmit.yml
+++ /dev/null
@@ -1,17 +0,0 @@
----
-platforms:
-  ubuntu1404:
-    build_targets:
-    - "..."
-    test_targets:
-    - "..."
-  ubuntu1604:
-    build_targets:
-    - "..."
-    test_targets:
-    - "..."
-  macos:
-    build_targets:
-    - "..."
-    test_targets:
-    - "..."
diff --git a/buildkite/pipelines/bazel-skylib-postsubmit.yml b/buildkite/pipelines/bazel-skylib-postsubmit.yml
deleted file mode 100644
index dd13f44..0000000
--- a/buildkite/pipelines/bazel-skylib-postsubmit.yml
+++ /dev/null
@@ -1,17 +0,0 @@
----
-platforms:
-  ubuntu1404:
-    build_targets:
-    - "..."
-    test_targets:
-    - "..."
-  ubuntu1604:
-    build_targets:
-    - "..."
-    test_targets:
-    - "..."
-  macos:
-    build_targets:
-    - "..."
-    test_targets:
-    - "..."
diff --git a/buildkite/pipelines/bazel-toolchains-postsubmit.yml b/buildkite/pipelines/bazel-toolchains-postsubmit.yml
deleted file mode 100644
index b9c1aa9..0000000
--- a/buildkite/pipelines/bazel-toolchains-postsubmit.yml
+++ /dev/null
@@ -1,28 +0,0 @@
----
-platforms:
-  ubuntu1404:
-    test_targets:
-    - "//test:debian-jessie-autoconfig_test"
-    - "//test:debian-jessie-bazel-head-autoconfig_test"
-    - "//test:debian-jessie-custom-bazel-version-autoconfig_test"
-    - "//test:debian-jessie-custom-bazel-rc-version-autoconfig_test"
-    - "//test:ubuntu-xenial-autoconfig_test"
-    - "//test:ubuntu-xenial-bazel-head-autoconfig_test"
-    - "//test:ubuntu-xenial-custom-bazel-version-autoconfig_test"
-    - "//test:ubuntu-xenial-custom-bazel-rc-version-autoconfig_test"
-    - "//test:debian8_clang_autoconfig_test"
-    - "//rules:debian8-clang-0.2.0-bazel_0.9.0-autoconfig_test"
-    - "//rules:debian8-clang-0.3.0-bazel_0.10.0-autoconfig_test"
-  ubuntu1604:
-    test_targets:
-    - "//test:debian-jessie-autoconfig_test"
-    - "//test:debian-jessie-bazel-head-autoconfig_test"
-    - "//test:debian-jessie-custom-bazel-version-autoconfig_test"
-    - "//test:debian-jessie-custom-bazel-rc-version-autoconfig_test"
-    - "//test:ubuntu-xenial-autoconfig_test"
-    - "//test:ubuntu-xenial-bazel-head-autoconfig_test"
-    - "//test:ubuntu-xenial-custom-bazel-version-autoconfig_test"
-    - "//test:ubuntu-xenial-custom-bazel-rc-version-autoconfig_test"
-    - "//test:debian8_clang_autoconfig_test"
-    - "//rules:debian8-clang-0.2.0-bazel_0.9.0-autoconfig_test"
-    - "//rules:debian8-clang-0.3.0-bazel_0.10.0-autoconfig_test"
diff --git a/buildkite/pipelines/bazel-watcher-postsubmit.yml b/buildkite/pipelines/bazel-watcher-postsubmit.yml
deleted file mode 100644
index dd13f44..0000000
--- a/buildkite/pipelines/bazel-watcher-postsubmit.yml
+++ /dev/null
@@ -1,17 +0,0 @@
----
-platforms:
-  ubuntu1404:
-    build_targets:
-    - "..."
-    test_targets:
-    - "..."
-  ubuntu1604:
-    build_targets:
-    - "..."
-    test_targets:
-    - "..."
-  macos:
-    build_targets:
-    - "..."
-    test_targets:
-    - "..."
diff --git a/buildkite/pipelines/buildtools-postsubmit.yml b/buildkite/pipelines/buildtools-postsubmit.yml
deleted file mode 100644
index a25fd60..0000000
--- a/buildkite/pipelines/buildtools-postsubmit.yml
+++ /dev/null
@@ -1,11 +0,0 @@
----
-platforms:
-  ubuntu1404:
-    test_targets:
-    - "//:tests"
-  ubuntu1604:
-    test_targets:
-    - "//:tests"
-  macos:
-    test_targets:
-    - "//:tests"
diff --git a/buildkite/pipelines/migration-tooling-postsubmit.yml b/buildkite/pipelines/migration-tooling-postsubmit.yml
deleted file mode 100644
index dd13f44..0000000
--- a/buildkite/pipelines/migration-tooling-postsubmit.yml
+++ /dev/null
@@ -1,17 +0,0 @@
----
-platforms:
-  ubuntu1404:
-    build_targets:
-    - "..."
-    test_targets:
-    - "..."
-  ubuntu1604:
-    build_targets:
-    - "..."
-    test_targets:
-    - "..."
-  macos:
-    build_targets:
-    - "..."
-    test_targets:
-    - "..."