Is Thermoswitch needed

[bolobass80]

I was having intermitten overheat buzzer issues, so I changed my thermo sensor. Upon doing so I noticed another sensor just below the thermo sensor that had been disconnected by the previous owner ( The one in the picture in http://frayedknotrocks.com/ox66.htm with the blue and brown wire, wires are clipped). I looked it up and it says its a thermo switch assembly.

Is this needed? what am I risking with it disconnected.

Thanks in advance for info

[boats.net]

Couldn't tell from picture which one had the wire cut, the one that screws into top of block with blue and black wires operates temp gauge in dash all the rest of them need to operational.