I can't find the delete button in the tab "Custom SEF url".
How is possible delete custom SEF url?

I use joomla 1.5.23 and artio joomsef 3.8.1

I have also attached a screenshot

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No one knows how is possible delete custom SEF url?

If I understand you correctly what you want to do is this:

URL manager->custom SEF URLs tab

choose the ones you want to delete.

Go to the top of that page and you will find two drop down menus.

Here you can choose what you want to do.

Hope that helps :)