If you put 退社 into a dictionary for example, you will get translations such as "leave work". However, if you are asking this question at work, everyone knows you are talking about someone leaving the workplace, therefore you do not need to mention 'work' in your question.
The main two ways to express 退社 are "go home" or "leave" (if the person you are talking to knows that you mean "leave work").
「退社」を辞書で検索すると、"leave work"などの翻訳が出てきますが、
職場でこの質問をすれば、workから帰るという意味なのが共通認識になりますので、
Did Mr Suzuki leave work already?などは言わないです。
「退社」を英語にすると、主に leave と go homeの二つの言い方が使われています。
This answer is a polite way of asking if someone has finished their work for the day and left the office or other work place.
This answer is not assuming that Suzuki-san has gone home as he/she may have gone somewhere else other than their home.
To knock off means to stop work. To hit the road means to start a journey (in this case home). If you make tracks, it means you leave the place where you are. With all of the above example sentences you may use the past simple or present perfect form. If you use 'yet' or 'already' the present perfect form is preferred.
"To knock off"は「作業を辞める」という意味です。"To hit the road"は「旅を始める」（この場合は、家に帰る）という意味です。"Make tracks"は「その場から去る」ということです。
上記例文はすべて現在形及び過去形の両方使えます。もし"yet"または"already"が入る際は、現在完了形を使います。
If you are not sure where a colleague or co-worker is you might be worried so you might ask if they have gone home you can say 'did Suzuki-san go home already?' or 'Has Suzuki-san already gone home?' if you are speaknig to a manager you might want to be more formal and not assume if someone has left and get them in trouble so you would say 'Has Suzuki-san finished for the day?'
同僚がどこにいるのか分からないなら、心配かもしれませんね。ですから、次のように聞けます。
'Did Suzuki-san go home already?'（鈴木さんはもう家に帰りましたか）
または、
'Has Suzuki-san already gone home?'（鈴木さんはもう家に帰りましたか）
上司に対して言うなら、よりフォーマルな言い方で、また帰ったかという聞き方だとその人をトラブルに巻き込む可能性もあるのでこれもやめた方が良いかもしれません。
'Has Suzuki-san finished for the day?'
（鈴木さんはもう今日は仕事を終えましたか）
Is Ms. Shizuki still here, or did she go home already?
Did Mrs. Shizuki already leave for the day?
These are all formal and common questions to ask if the person has already left. All three of these sentences can be used if you want to know if the person has left and will not be expected to return that same day. We typically use the phrases 'Has (person) gone', 'Did (person) go home', and 'Did (person) leave'. The word 'already' is optional and just refers to the person leaving sooner than expected.
イギリス 
アメリカ合衆国 
