You basically mash down on all the keys on the right side of your keyboard while you click the AE program file. You will get a dialogue that asks if you want to delete your preferences. The actual KB shortcut is Ctrl/Cmnd + Alt/Option + Shift + Click on app.
Another way is to open your preferences>general panel and click on reveal preferences in your finder/explorer window. Then close AE and either delete the file or rename it.
Thank you! arms
Rick is correct.
Yet another way is to use the Clear Settings command in the Sync Settings menu.