help: Document "Who can unsubscribe others from this stream?" setting.

- Updates "Remove others" row in "Stream permissions" tables.
- Adds a section to "Add or remove users from a stream" describing
  how to configure the new setting.
- Documents the new setting in "Create a stream".
- Documents "Message retention period" setting in "Create a stream".

Fixes #24340.

help/add-or-remove-users-from-a-stream.md

@@ -90,6 +90,29 @@ This method is useful if you need to remove one user from multiple streams.
 
 {end_tabs}
 
+## Configure who can remove users
+
+{!admin-only.md!}
+
+Organization administrators can configure who can remove other users from a
+public stream. For private streams, administrators must be subscribed to the
+stream to configure this setting.
+
+{start_tabs}
+
+{relative|stream|all}
+
+1. Select a stream.
+
+{!select-stream-view-general.md!}
+
+1. Under **Stream permissions**, configure
+   **Who can unsubscribe others from this stream?**
+
+{!save-changes.md!}
+
+{end_tabs}
+
 ## Related articles
 
 * [Browse and subscribe to streams](/help/browse-and-subscribe-to-streams)

help/create-a-stream.md

@@ -44,6 +44,12 @@ There are several parameters you can set while creating a stream. All but
 
 * **Who can post to the stream?**: See [Stream permissions](/help/stream-permissions).
 
+* **Who can unsubscribe others from this stream?**: See
+  [Add or remove users from a stream](/help/add-or-remove-users-from-a-stream#configure-who-can-remove-users).
+
+* **Message retention period**: See
+  [Message retention policy](/help/message-retention-policy#configure-message-retention-policy-for-individual-streams).
+
 * **Choose subscribers**: You can copy the membership from an existing stream or
   [user group](/help/user-groups), add all users, or enter users one by one.
 

help/stream-permissions.md

@@ -64,6 +64,7 @@ administrator can access private stream messages:
 | Join                  | ✔          | ✔   | ✔  |
 | Unsubscribe           | ◾           | ◾    | ◾   | ◾
 | Add others            | ✔          | ✔   | ✔  |
+| Remove others         | ✔          | ✶   | ✶  | ✶
 | See subscriber list   | ✔          | ✔   | ✔  | ◾
 | See full history      | ✔          | ✔   | ✔  | ◾
 | See estimated traffic | ✔          | ✔   | ✔  | ◾
@@ -71,17 +72,17 @@ administrator can access private stream messages:
 | Change the privacy    | ✔          |            |           |
 | Rename                | ✔          |            |           |
 | Edit the description  | ✔          |            |           |
-| Remove others         | ✔          |            |           |
 | Delete                | ✔          |            |           |
 
 <span class="legend_symbol">&#10004;</span><span class="legend_label">Always</span>
 
 <span class="legend_symbol">&#9726;</span><span class="legend_label">If subscribed to the stream</span>
 
-<span class="legend_symbol">&#10038;</span><span class="legend_label">[Configurable](/help/stream-sending-policy).  Owners,
+<span class="legend_symbol">&#10038;</span><span class="legend_label">
-administrators, and members can, by default, post to any public
+Configurable. See [Stream posting policy](/help/stream-sending-policy) and
-stream, and guests can only post to public streams if they are
+[Configure who can remove users](/help/add-or-remove-users-from-a-stream#configure-who-can-remove-users)
-subscribed.</span>
+for details.
+</span>
 
 ### Private streams
 
@@ -92,6 +93,7 @@ subscribed.</span>
 | Join                  |                   |            |           |
 | Unsubscribe           | &#9726;           | &#9726;    | &#9726;   | &#9726;
 | Add others            | &#9726;           | &#9726;    | &#9726;   |
+| Remove others         | &#10004;          | &#10038;   | &#10038;  | &#10038;
 | See subscriber list   | &#10004;          | &#9726;    | &#9726;   | &#9726;
 | See full history      | &#10038;          | &#10038;   | &#10038;  | &#10038;
 | See estimated traffic | &#10004;          | &#9726;    | &#9726;   | &#9726;
@@ -99,15 +101,18 @@ subscribed.</span>
 | Change the privacy    | &#9726;           |            |           |
 | Rename                | &#10004;          |            |           |
 | Edit the description  | &#10004;          |            |           |
-| Remove others         | &#10004;          |            |           |
 | Delete                | &#10004;          |            |           |
 
 <span class="legend_symbol">&#10004;</span><span class="legend_label">Always</span>
 
 <span class="legend_symbol">&#9726;</span><span class="legend_label">If subscribed to the stream</span>
 
-<span class="legend_symbol">&#10038;</span><span class="legend_label">[Configurable](/help/stream-sending-policy), but at minimum
+<span class="legend_symbol">&#10038;</span><span class="legend_label">
-must be subscribed to the stream.</span>
+Configurable, but at minimum must be subscribed to the stream.
+See [Stream posting policy](/help/stream-sending-policy) and
+[Configure who can remove users](/help/add-or-remove-users-from-a-stream#configure-who-can-remove-users)
+for details.
+</span>
 
 ## Related articles