An image processing apparatus for decoloring a decolorable toner image formed on one or more sheets, includes an image processing unit comprising a controller and an image heating section, wherein the image heating section is selectively operable at a toner fixing temperature and an image decoloring temperature that is higher than the toner fixing temperature, a communication interface configured to communicate with an external decoloring device, and a user input section. The controller, upon receiving a request to decolor one or more sheets that is made through the user input section, determines which of the image heating section and the external decoloring device will be the first available to decolor the one or more sheets.