ROLLBACK transactions (TCL Commands) | Oracle SQL fundamentals

ROLLBACK tells #Oracle to roll back the entire transaction. In your case, both the #INSERT and the #DELETE are part of the same transaction so the #ROLLBACK reverses both operations. That returns the #database to the state it was in immediately following the CREATE TABLE statement.
In Oracle, the ROLLBACK statement is used to undo the work performed by the current transaction or a transaction that is in doubt.