SQL> delete from b$gc_count_temp a INNER JOIN COMPLEMENTS ON b$gc_count_temp.CON
NECTION_ID_TEMP=COMPLEMENTS.feature_conn_id
  2  WHERE a.current_designation is null and a.current_low is null and a.current
_high is null;

delete from b$gc_count_temp a INNER JOIN COMPLEMENTS ON b$gc_count_temp.CONNECTI
ON_ID_TEMP=COMPLEMENTS.feature_conn_id
                              *
ERROR at line 1:
ORA-00933: SQL command not properly ended

delete from your_table
where id in (select some_id from another_table
             where ...
            )

delete from emp e
where exists (select 1 
                      from dept d 
                      where e.deptno=d.deptno --correlation part
                      and d.dname='ACCOUNTING')
;

SCOTT@orcl_11gR2> create table b$gc_count_temp
  2    (connection_id_temp  number primary key,
  3  	current_designation number,
  4  	current_low	    number,
  5  	current_high	    number)
  6  /

Table created.

SCOTT@orcl_11gR2> insert into b$gc_count_temp values
  2    (1, null, null, null)
  3  /

1 row created.

SCOTT@orcl_11gR2> insert into b$gc_count_temp values
  2    (2, 3, 4, 5)
  3  /

1 row created.

SCOTT@orcl_11gR2> create table complements
  2    (feature_conn_id     number primary key)
  3  /

Table created.

SCOTT@orcl_11gR2> insert into complements values (1)
  2  /

1 row created.

SCOTT@orcl_11gR2> insert into complements values (2)
  2  /

1 row created.

SCOTT@orcl_11gR2> 
SCOTT@orcl_11gR2> delete from
  2  	    (select *
  3  	     from   b$gc_count_temp a
  4  	     INNER JOIN COMPLEMENTS
  5  	     ON a.CONNECTION_ID_TEMP=COMPLEMENTS.feature_conn_id
  6  	     WHERE a.current_designation is null
  7  	     and a.current_low is null
  8  	     and a.current_high is null)
  9  /

1 row deleted.

SCOTT@orcl_11gR2> select * from b$gc_count_temp
  2  /

CONNECTION_ID_TEMP CURRENT_DESIGNATION CURRENT_LOW CURRENT_HIGH
------------------ ------------------- ----------- ------------
                 2                   3           4            5

1 row selected.

SCOTT@orcl_11gR2> select * from complements
  2  /

FEATURE_CONN_ID
---------------
              1
              2

2 rows selected.

SCOTT@orcl_11gR2>