Dissable autocommit in sql developer web. Autonomous Database - Oracle cloud

Question

I am doing some tests in Oracle Cloud using SQL Developer web.

I want to use the rollback command, but it does not work.

My table "t_test" is empty:

I add a row:

I can select that row:

I want to rollback:

It seems to work, but the record does not dissapear:

How can I dissable the autocommit?

UPDATE.

I tried to use set autocommit off, and it did not work

Thanks.