Take out of circulation is a term used to describe the process of retiring something, usually a product or service. This means that it is no longer available for use or purchase. It is often done when a company decides to discontinue a product or service due to lack of demand or profitability. The term can also be used to refer to the retirement of an individual from a job or position. In this case, the crossword solution is 'RETIRE, ' which is a six-letter word meaning to take out of circulation.