sql-plan-replayer: add description for PLAN REPLAYER CAPTURE REMOVE (…

…#17582)

sql-plan-replayer.md

@@ -269,6 +269,29 @@ The method of downloading the file of `PLAN REPLAYER CAPTURE` is the same as tha
 >
 > The result file of `PLAN REPLAYER CAPTURE` is kept in the TiDB cluster for up to one week. After one week, TiDB deletes the file.
 
+### Remove the capture tasks
+
+If a capture task is no longer needed, you can remove it using the `PLAN REPLAYER CAPTURE REMOVE` statement. For example:
+
+```sql
+mysql> PLAN REPLAYER CAPTURE '077a87a576e42360c95530ccdac7a1771c4efba17619e26be50a4cfd967204a0' '4838af52c1e07fc8694761ad193d16a689b2128bc5ced9d13beb31ae27b370ce';
+Query OK, 0 rows affected (0.01 sec)
+
+mysql> SELECT * FROM mysql.plan_replayer_task;
++------------------------------------------------------------------+------------------------------------------------------------------+---------------------+
+| sql_digest                                                       | plan_digest                                                      | update_time         |
++------------------------------------------------------------------+------------------------------------------------------------------+---------------------+
+| 077a87a576e42360c95530ccdac7a1771c4efba17619e26be50a4cfd967204a0 | 4838af52c1e07fc8694761ad193d16a689b2128bc5ced9d13beb31ae27b370ce | 2024-05-21 11:26:10 |
++------------------------------------------------------------------+------------------------------------------------------------------+---------------------+
+1 row in set (0.01 sec)
+
+mysql> PLAN REPLAYER CAPTURE REMOVE '077a87a576e42360c95530ccdac7a1771c4efba17619e26be50a4cfd967204a0' '4838af52c1e07fc8694761ad193d16a689b2128bc5ced9d13beb31ae27b370ce';
+Query OK, 0 rows affected (0.01 sec)
+
+mysql> SELECT * FROM mysql.plan_replayer_task;
+Empty set (0.01 sec)
+```
+
 ## Use `PLAN REPLAYER CONTINUOUS CAPTURE`
 
 After `PLAN REPLAYER CONTINUOUS CAPTURE` is enabled, TiDB asynchronously records the applications' SQL statements with the `PLAN REPLAYER` method according to their `SQL DIGEST` and `PLAN DIGEST`. For SQL statements and execution plans that share the same DIGEST, `PLAN REPLAYER CONTINUOUS CAPTURE` does not record them repeatedly.