As far as I can see you are referring to the row indicators in each grid control. You may remove it through setting RadGridView's RowIndicatorVisibility property to Collapsed. If you want to alter its appearance you may predefine the template of GridViewRow using Microsoft Expression Blend and modify the part named PART_IndicatorPresenter which hosts the elements of the row's indicator in the way you need.
Keep in mind that the styles used in our themes are theme specific. You should predefine the appearance of the row agains the Metro theme. We ship our themes as separate projects and you may get the xaml files for all Telerik themes from the Themes folder of your personal installation. Find the xaml file named GridViewRow.xaml in Metro theme project, copy it to your current project and modify it based on your requirements. Once you set the Metro theme to RadGridView this style will be handled correspondingly.
If you need sample project I will be glad to prepare a small demo illustrating this approach.
the Telerik team
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