Welcome to Orchid Board
I think if the plant is happy (you mention it's still growing leaves which seems happy to me) then you can just leave them. Usually you would cut back the spikes if they stop blooming and dry up (some people including me cut them back once the flowers are gone, even if they don't dry up).
If you think it's becomeing too leggy then you could cut them back. You would then have to wait for new spikes to start. That can often be in the Autum (Fall) with a drop in temps.
The only other thing I would say is don't cut them part back to force new side spikes. This technique while it might give some more flowers can weaken the plant, especially if done repeatedly. If it's just choosing to keep flower on it's own though it will only keep going if it's strong enough so you should not have this problem.