The option is available at the "Maximum" security level.
Enabling this option makes it impossible to change the domain registrant or registrar without a personal visit by the current registrant of the Rucenter office.
To enable the option:
1. In your personal account, go to the section "Active services → My domains".
2. Select the domain for which the "Maximum" security level is provided.
3. Go to the "Security" tab.
4. Go to the "Domain operation restrictions" option and click "Settings".
5. On the settings page, click "Enable".
Disabling this option with Maximum security level enabled is only available by the domain registrant visiting the Rucenter office in person.