Block Section

Check some of THESE SOLUTIONS to accomplish your goal. The switch can be located in the roadbed or mounted anywhere on the layout or control panel.

Remove the center /red jumper wire.

The straight side of the switch will receive power from the main line.

In addition to robs suggestion. Any common toggle from the local hardware store will suffice and you can run a hot wire in to the toggle then out to the track connecting to one of the wire tabs found underneath the fastrack on you siding and mount the toggle where ever you like.

A single pole single throw should be adequate

I use a single pole double throw to toggle between two parallel sidings.

My layout has a number of complicated switch and automatic controlled block sections. Whatever you do, keep a good record, best with diagrams. It will pay off.

John:

I am not that familiar with Fastrack but as an alternative you can isolate the middle rail of spur at the end of the turnout. Use the same ground but run the power wire to a SPST on/off toggle switch at the control board. The other end of the switch will go to the normal power run.

Joe

John Patrick - Seems from your original post you understand what to do.  Other responders to your post have show creative ways to incorporate toggle switches in the Fastrack base.  Also, responders have suggested ways to create your own insulated block section for ordinary track sections.  Just one small terminology point:  it's "single pole double throw", not "single pull double throw".  Also as stated, you can use a simpler/lower cost "single pole single throw (SPST)" toggle switch to turn off power to one of your sidings.  If you want to turn off power to a second siding independent of the first you will need a second SPST switch.