From Yuku Help

Warned

This page allows you to view all your warned members in one go. The features on this page are mostly the same as the all page. You can also view all the same members by using the status filter on the all page.

You can warn your members by using the Edit a single member page or Edit bulk members page.

You'll find the warn button in the Custom settings box. You cannot warn your admins.

When you warn a member, a note is added to their edit page with the date on which you warned them. You can warn a member as many times as you like, but if they get a third warning within 30 days, they will automatically be banned.

You can also choose to send them a pm to tell them that they are being warned. If you choose not to send a pm, then their warning is unknown to them.