A server for controlling an image forming system according to an embodiment includes an interface that receives, from a user device, document data and instructions to print the document data. A storage section stores the document data. A controller determines a printing mode of the document data based on property information included in the document data. The controller selects for printing the document data, only one of a non-erasable image forming apparatus and an erasable image forming apparatus based on the determined printing mode. The controller controls a display device to display a screen for selecting an erasable printing mode designation if the printing mode is determined to be a non-erasable printing mode.