If you unbutton your collar, remove your tie.

如果你解开领扣，就把领带摘下来。

youdao

His tie was pulled loose and his collar hung open.

他的领带被扯松了，衣领敞开着。

《柯林斯英汉双解大词典》

He always wears a collar and tie for work.

他上班总是系着领带。

《牛津词典》

Another collar that goes well with a sport coat sans tie is the semi- or medium-spread collar as both "stand up on their own without a tie, " and don't flare out.

WSJ: Guide to Men's Shirt Collars: Which Styles Go With Which Occasions and Flatter the Face

Research suggests people regard police as "more professional" in a collar and tie, said a force spokesman.

BBC: Norfolk Police officers trial collar-and-tie uniform

Research now suggests people regard police as "more professional, honest and approachable" in a collar and tie, the force says.

BBC: Norfolk police uniform shirts set for switch