diff --git a/src/typeguard/_checkers.py b/src/typeguard/_checkers.py
index 34bff23..145312f 100644
--- a/src/typeguard/_checkers.py
+++ b/src/typeguard/_checkers.py
@@ -405,7 +405,10 @@ def check_union(
     formatted_errors = indent(
         "\n".join(f"{key}: {error}" for key, error in errors.items()), "  "
     )
-    raise TypeCheckError(f"did not match any element in the union:\n{formatted_errors}")
+    try:
+        raise TypeCheckError(f"did not match any element in the union:\n{formatted_errors}")
+    finally:
+        del errors
 
 
 def check_uniontype(