People commonly use USB flash memory because of its convenience and portability. It stores various data such as documents, pictures, certificates, and private data (e.g., passwords, account numbers). These data, especially private data, should not be revealed to the outside. However, even when the stored data is deleted, these data can be recovered using data recovery programs. To prevent this problem, various techniques have been proposed. In this paper, we review previous methods and analyze the security of these methods. We then propose a secure deletion method that requires only one write or erase operation. Our benchmark study shows the proposed method satisfies government agencies’ requirements for the secure deletion and performs better than the previous methods. The main contribution of this paper is two-fold: (1) we show our method satisfies the government’s recommendations for secure data deletion and (2) our proposed method has better performance than previously proposed method because only one write or write-then-erase operation is performed.