Is it ensure, insure, or assure?
1680s, from French détacher "to detach, untie," from Old French destachier, from des- "apart" + attachier "attach" (see attach). Related: Detached; detaching.
detach de·tach (dĭ-tāch')v. de·tached, de·tach·ing, de·tach·es
To separate or unfasten; disconnect.
To remove from association or union with something.