Minor textual cleanups.

Split up some overly long sentences into smaller ones to improve readability. Remove some redundancies in sentences and add () around the room history export example. 

content/rooms/delete.en.md

@@ -8,12 +8,12 @@ weight: 30
 ## Delete rooms and leave rooms
 
 
-When leaving rooms, they no longer appear in the room list (left column). If the last person in the room leaves the room, the room is still in the archive for 7 days, but is then permanently deleted.
+When leaving rooms, they no longer appear in the room list (left column). If the last person in the room leaves, the room is archived for 7 days. After that, is it deleted permanently.
 
 ![Room settings with the selection Leave](/images/01_Leave_en.png)
 
-As administrator of the room, you should "kick" all members of the room first (remove them from the room). Then you should leave the room as the last person and thus you initiate the later deletion by the server.
+As room administrator, you should "kick" (remove) all members of the room first. Then you should leave the room as the last person to initiate the later deletion by the server.
 
 ![Room settings kick of User](/images/01_kickUser_en.png)
 
-An export of the room history e.g. into a .txt or .html file is not yet possible: https://github.com/vector-im/element-web/issues/2630
+An export of the room history (e.g. into a .txt or .html file) is not yet possible: https://github.com/vector-im/element-web/issues/2630