Uncaught (in promise) TypeError: files is not iterable at uploadFile. Help me please

const [files, setFiles] = React.useState([]);

const uploadFile = async event => { event.preventDefault();

const file = event.target.files[0];

let formData = new FormData();
formData.append('file', file);

let response = await api.post('/api', formData);
console.log(response);

if (response.status === 200) {
  setFiles([response, ...files]);
}

};

const deleteFile = async filenames => { console.log(JSON.stringify(filenames));

for (let filename of filenames) {
  console.log(filename);
  await api.delete(`/api`, filename);
}
setFiles({ filename: '' });

};

<Form
            onSubmit={handleSubmit}
          >
            <FormField
              name="filename"
              htmlFor="input-id"
              required
            >
              <FileInput
                id="filename"
                name="filename"
                onChange={uploadFile}
                value={files.filename}
              />
            </FormField>

            <Button
              onClick={() => deleteFile(files)}
            >
              Удалить
            </Button>
          </Form>