Restore lost administrator role to administrator user

• Type: Bug
• Status: Closed
• Resolution: Completed
• Affects Version/s: 5.2.3
• Fix Version/s: 5.2.3
• Component/s: User Management
• Labels: None
• Environment: Liferay 4.2.2

On one of our environments the administrator user has mistakenly deleted his own administrator role.
Since he is the only administrator user on that system he cannot restore administrator rights to himself.

Is there a simple way to restore the administrator user?

If not, note that we cannot delete/reset the Liferay database.
If the only solution is to manipulate the Liferay database can you please direct me to the table and values that we should change?

Thanks.