Remove unused using declarations.

verible/verilog/analysis/symbol-table_test.cc

diff --git a/verible/verilog/analysis/symbol-table_test.cc b/verible/verilog/analysis/symbol-table_test.cc
index 1354ff8..cec3c88 100644
--- a/verible/verilog/analysis/symbol-table_test.cc
+++ b/verible/verilog/analysis/symbol-table_test.cc
@@ -51,8 +51,6 @@
 using testing::ElementsAreArray;
 using testing::HasSubstr;
 using verible::file::Basename;
-using verible::file::CreateDir;
-using verible::file::JoinPath;
 using verible::file::testing::ScopedTestFile;
 
 // An in-memory source file that doesn't require file-system access,