delete from yourTableName where yourColumnName=yourValue limit 1;

mysql> create table DemoTable
   -> (
   -> Amount int
   -> );
Query OK，0 rows affected (1.38 sec)

mysql> insert into DemoTable values（50）;
Query OK，1 row affected (0.23 sec)
mysql> insert into DemoTable values（100）;
Query OK，1 row affected (0.36 sec)
mysql> insert into DemoTable values（50）;
Query OK，1 row affected (0.59 sec)
mysql> insert into DemoTable values（70）;
Query OK，1 row affected (0.18 sec)
mysql> insert into DemoTable values（90）;
Query OK，1 row affected (0.13 sec)
mysql> insert into DemoTable values（50）;
Query OK，1 row affected (0.23 sec)

mysql> select *from DemoTable;

+--------+
| Amount |
+--------+
|     50 |
|    100 |
|     50 |
|     70 |
|     90 |
|     50 |
+--------+
6 rows in set (0.00 sec)

mysql> delete from DemoTable where Amount=50 limit 1;
Query OK，1 row affected (0.39 sec)

mysql> select *from DemoTable;

+--------+
| Amount |
+--------+
|    100 |
|     50 |
|     70 |
|     90 |
|     50 |
+--------+
5 rows in set (0.00 sec)