Usually, if that species is not protected, you may kill it. However, you must do the deed humanely! I am a pet snake owner. I have snakes around my house and in the hedge. I leave them alone and they avoid me. I wish I never have to kill one. They are not venomous and they keep to themselves. They also keep the possum population in check.
Snake eats hummingbird: the circle of life... what an I say? Nature is red in tooth and claw.
I like ecrane's sugestion of exclusion. While at our cabin in NC last week I saw a black rat snake catch and devour a very young rabbit. I was sad for the cute little critter but I'm glad to have the snake around to help with rodent control.
i would be very interested in finding out what kind of snake this is. most snakes grab and hold on, they do not bite and then wait for the prey to die. also, is it constantly wrapped around the feeder? maybe move the feeder to a place less hospitable to the snake.