addressed location align bug

Author: sxzh93

src/include/parser/alter_statement.h

@@ -49,18 +49,18 @@ class AlterTableStatement : public TableRefStatement {
     }
     if (dropped_names != nullptr) {
       for (auto name : *dropped_names) {
-        delete name;
+        free(name);
       }
       delete dropped_names;
     }
     if (changed_type_columns != nullptr) {
       delete changed_type_columns;
     }
     if (oldName) {
-      delete oldName;
+      free(oldName);
     }
     if (newName) {
-      delete newName;
+      free(newName);
     }
   }