Comment by jeroenhd

I don't think you can, but you could open a popup over the target to hide the authorisation page to make it a little less obvious. JS also has a window.close() function for opened windows, but I believe browsers might show a warning when you try that on an external origin.

One could also confuse the user by spawning a whole bunch of tabs for other services after clicking the authorise button, making the user think something weird is going on and closing all the tabs that just popped up without realising they clicked the authorisation button.