A deletable blockchain has been proposed recently to change the immutability of the traditional blockchain. However, the users' identities and transaction contents are all public in the scheme, and the public data may reveal the users' privacy. In order to protect the privacy of the users, we propose a privacyprotected deletable blockchain based on the proof-of-space consensus mechanism, which does not rely on complex cryptographic tools or any trusted party. In order to satisfy full transparency and accountability in an anonymous environment, we use a traceable ring signature or a Pedersen commitment scheme to disclose the users' real identities or the real transaction contents respectively according to different deletion reasons. During the deletion process, we propose a linkable multi-signature scheme, which allows multiple users to generate a valid signature by using their one-time addresses as pseudonyms to protect their identity privacy. Moreover, the proposed multi-signature scheme can link two sub-signatures if they are generated by the same malicious user. Finally, we simulate the generation and deletion process of a block under the proof-of-space consensus mechanism and give the time of generating and deleting a block. The experimental results prove the efficiency and feasibility of our proposed scheme. INDEX TERMS Blockchain, privacy protection, deletable, linkable multi-signature. XIANJI CAI received the B.S. degree in electronics and information engineering from Shanghai University, China, in 2018, where she is currently pursuing the M.S. degree. Her research interests are blockchain security and cryptocurrencies. YANLI REN received the M.S. degree in applied mathematics from Shaanxi Normal University, China, in 2005, and the Ph.D. degree in computer science and technology from Shanghai Jiao Tong University, China, in 2009. She is currently a Professor with the School of Communication and Information Engineering, Shanghai University, China. She has published more than 60 articles on international journals and conference papers. Her research interests include applied cryptography, secure outsourcing computing, and network security.