Hi,its always better to have these thing working as they are ment to,if you look at the exspantion tank where you fill it up with coolent you will see a switch with wires comeing from it ,it will ether be in the lid or on thtank some where,take the wires off and join them together then start the car if the light has gone out you will need to replace the sensor,all the best.

The coolant sensor is normally in the top tank of the radiator and if there is insufficient coolant in that tank it will put the sensor on
check at the radiator cap not the reservoir cap
next it works by having a current pass through the coolant to hold a relay out that puts the light or buzzer
check for broken wires or bad connections
it is not a problem but it is a first stage in problem notification that will tell you long before the engine is cooked say from a blown radiator hose or radiator tank failure
best have it fixed by an accredited service shop