Unhitch
Full definition of unhitch
Verb
- To disconnect; to detach; to undo that which is hitched.
- 1877, Anna Sewell, Black Beauty Chapter 23http://en.wikisource.org/wiki/Black_Beauty/23There is no knowing what further mischief she might have done, had not York promptly sat himself down flat on her head, to prevent her struggling, at the same time calling out, "Unbuckle the black horse! run for the winch and unscrew the carriage pole; cut the trace here—somebody, if you can't unhitch it."