how to get rid of beavers?

well, since you asked: the only thing one can do to thwart the rodents without killing them is to wrap the trunks of the trees you want to preserve with fencing of some sort. Otherwise the trees are theirs..they will be back at some point in the future regardless of your eradication attempts!!! Unless, of course, beaver hats and coats come back in fashion in your life time. But then, of course, polar fleece has precluded that from happening anytime soon.

Beavers have more right than anybody to kill trees...they are just acting in nature as they should. Let them be.

You can call animal control or hire a trapper to remove them from your premises.