從位子上被換下來
把馬鞍換成一個職位或一個名次。動作完全一樣：本來坐得穩穩的被弄下來，而且一定是「原本有人（或有東西）在那裡」，這正是它跟 defeat、replace 的差別。
verb · C1
To take a powerful job or position away from someone, especially by beating them in an election or a vote.
把（在位者）拉下台
核心畫面
Think of someone sitting firmly in a saddle, and then one sudden movement that puts them on the ground. The seat stays; the person in it does not. English lets that seat be a saddle, a job, a rank at the top of a list, or a belief people have sat on for years — and the verb does the same thing to all of them.
可以想成一個人穩穩坐在馬鞍上，然後一個突然的動作，人就落地了。位子還在，坐著的人不在了。英文把這個「位子」延伸得很廣…更多收起
可以想成一個人穩穩坐在馬鞍上，然後一個突然的動作，人就落地了。位子還在，坐著的人不在了。英文把這個「位子」延伸得很廣：馬鞍、職位、排行榜第一名，甚至一個大家相信很久的想法。這個動詞對它們做的事情都是同一件。From the word’s history
The source gives un- + seat, where seat means 'to provide with a place to sit'. So the word literally undoes sitting: whatever was in the seat is out of it.
來源資料寫這個字是 un- 加 seat，seat 的意思是「讓人有位子坐」。所以字面就是把「坐著」這件事倒過來：本來在位子上的，現在不在了。
Wiktionary entry for unseat, etymology: “From un- + seat (‘to provide with a place to sit’).” (packet ref kaikki:3f6f69a190036ae4:672111574:29663)
From the picture
Also in this word
verb · C1
If a horse, a bike or something similar unseats a rider, it throws them off so that they fall from where they were sitting.
把（騎乘的人）摔下來