Definition of "unsash"

I know how to make her run mad with passion that has nothing to do with books and animals. I know how to make her unpin her hair, unsash her gown, unhook — But he hadn't said a word, only allowed the devil's own smile to lift one corner of his mouth.

1994, Terri Sprenger, Nighthawk's Woman, page 358

She watched him walk to the bed set on its foot-high dais, watched him walk in his bare feet, big feet that were really quite beautiful, watched him pull the covers back, unsash the dressing gown, shrug it off, and naked as a black-haired god, climb into the bed.

1994, Catherine Coulter, The Wyndham Legacy

But though she felt curious about the toys Ron had phoned to tell her he was bringing, she wished she could open the front door to Dirk and unsash her robe for him.

2011, Michael Scofield, Acting Badly: A Novel, page 161

My job was to perform the Sashing Ceremony on the banks of the Esk. I should unsash the Honest Lad and Lass of 1953 with thanks for their services and then I should charge and sash the Honest Lad and Lass of 1954.

1971, Sir Compton Mackenzie, My life and times - Volume 10, page 36

First, close the doors, unsash the curtains, turn off all the lights but the glass lamp.

2001, Liza Nelson, Playing Botticelli, page 115

"Shall I unsash the curtain, sir?" the boy asked, bowing meekly to Tarrington.

2003, Charles White, The Loyalist's Son, page 53

Last humorous final situation I'm likely to register; rest will be hysterically funny; femme hystérique; or hysterical: sits down and eats the chicken like tomorrow is prohibition on food; tip-toe on the bed, unsash shutter, peering out: a Moroccan with Spanish lady, some species of argument under the window: ...

1969, Ronald Tavel, Street of stairs, page 128