With Android 4.3 comes a new feature, restricted profiles. It allows creating new special "restricted" users, for which an admin user can control access to apps.
However, in addition to my own admin user, I already have a secondary user for my kid, which has all of the user-specific data, such as saved games. If I create a new restricted profile, those will be lost.
How can I convert an existing (secondary) user to a restricted profile?
Note for the interested: The restricted profiles feature doesn't provide a complete secure access block, but it works well as a hinderance and prevents accidental blunders - which happens to be excatly what I'm interested in.