Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!
You should remove it as well really as the pulleys should be changed as well.
But if for some reason you need to take it off without changing the pulleys, you need either a 3/8 square drive peg to rotate the tensioner with, or you can put a jubilee around the spring and do it up to close the spring and hence release the tension.