Best practice is to never create anything ad-hoc in the database, but use the scripts generated by mendix (m2ee).
In the absence of scripts something like the following might help:
SELECT 'CREATE INDEX ' || INDEX_NAME || ' ON '
|| TABLE_NAME || ' (' || COL_LIST || ',NEWCOLUMNNAME)'
FROM (
Select index_name,table_name,
LISTAGG(COLUMN_NAME || DECODE(DESCEND,'ASC','', ' ' || DESCEND), ',')
WITHIN GROUP (ORDER BY COLUMN_POSITION) AS COL_LIST
FROM SYS.ALL_IND_COLUMNS
GROUP BY index_name,table_name
);
This example assumes you may have indexes on multiple columns, indexes on single columns can also be achieved by a simpler statement.
You can spool the output to a file in sqlplus, edit it if needed, and run it in sqlplus (or some more advanced new tool...).
(example comes from stackoverflow: How to alter all indexes on an Oracle schema in one script (10G))