create table paym (method varchar2(100));

insert into paym values('PAY,PAY,PAY,PAY');
insert into paym values('ACP,PAY,PAY');
insert into paym values('PAY,ACP,ACP');
insert into paym values('PAY,PAY');

SELECT method ,
        COUNT(*) AS method_cnt ,
        LISTAGG(method, ',') WITHIN GROUP (ORDER BY method) AS List_Agg,
        REGEXP_REPLACE(LISTAGG(method, ',') WITHIN GROUP (ORDER BY method),'([^,]+)(,\1)+', '\1') AS List_Agg_Distinct
    FROM paym
    GROUP BY method

SQL> with
  2    data as (select method, rownum id from paym),
  3    words as (
  4      select distinct id, regexp_substr(method, '[^,]+', 1, column_value) word
  5      from data,
  6           table(cast(multiset(select level from dual
  7                               connect by level <= regexp_count(method,',')+1)
  8                      as sys.odciNumberList))
  9    )
 10  select listagg(word,',') within group (order by word) method
 11  from words
 12  group by id
 13  order by id
 14  /
METHOD
--------------------
PAY
ACP,PAY
ACP,PAY
PAY

4 rows selected.

select  xmlquery(('string-join(distinct-values(ora:tokenize("' || method || '",",")),",")' ) returning content) method
  from  paym
/

METHOD
---------
PAY
ACP,PAY
PAY,ACP
PAY

SQL>