A method is provided for controlling automatic deletion of medical images in a universal viewer system that shares the medical images between a cloud server and a plurality of healthcare facilities connected to the cloud server. The method is executed by the cloud server and includes: receiving, from a user at one of the healthcare facilities, an automatic deletion request that comprises a target deletion period and a deletion start time; determining, after the deletion start time has elapsed, a target medical image based on the target deletion period; retrieving an access history of the target medical image; terminating, in response to determining based on the access history that the target medical image is accessed by a plurality of users, the automatic deletion request without deleting the target medical image; storing in a memory a result of the automatic deletion request; and causing the result of the deletion request to be displayed on a display of at least one of the healthcare facilities.