The Route Ribbon tab is shown below.

Auto-Route

This will autoroute all tracks.

This is autoroute only selected tracks.

Manual

This will start manual routing.

If selected the manual routing will start on the top layer, else it will start on the bottom.

Unroute

This will unroute all routed tracks.

This will unroute all selected objects that are routed or have routed tracks connected to them.

This will unroute all selected tracks that are routed.

Dimming

This will turn on/off auto-dimming. When auto-dimming is on, all tracks that you are not routing will be dimmed. It enables you to more easily see the track you are routing.