Unauthorized (adjective)

Not having official permission or approval; not authorized.

Origin:

Late 16th century: from un- (expressing negation) + authorized.

Examples:

1. He made unauthorized changes to the software.
2. The unauthorized use of the company's name.
3. Unauthorized access to the network.
4. Unauthorized personnel are not allowed in the building.
5. The transaction was unauthorized and had to be reversed.