[ ] stronger warning that you are removing a route/area which is already on the topo
[ ] do we need a warning at all if the route/area is not already on the topo
[ ] if it is removed then it should be taken off the topo (note that refreshing the page will mean it is removed)
[ ] currently if we add back in the area/route then what was previously drawn returns. Is this a feature we want? I think it is a nice feature, in case somebody accidentally unlinked a route from a topo.
Not sure what we actually want to do here.