Overwrite file

When trying overwrite file the another user display the error.
"scp: /www/cad_produto_servico.xml: set mode: Operation not permitted"
but i can change name the file and delete it, why????

ps.: the file have full permission

If you are not owner of the file, you usually cannot change the file permissions. Turn off 'Set permissions' and/or 'Preserve timestamp' options.