Follow the steps for resetting to factory default on your 86U.
[Wireless] ASUS router Hard Factory Reset - Method 2 | Official Support | ASUS Global
If you can login to the 86U, resetting through the Web GUI is the easiest method and doesn't involve holding any buttons down or power cycling. Otherwise, as the linked article outlines, you can power it off, then hold down the WPS button, and power it on with the WPS button held down until the power light goes off. Let it reboot, and you're done. Reconfigure by manually entering in your router settings through the web UI.