Not sure why I made the effort, this will help you on your problem. Please give us more information next time as it makes it easier to understand your question -
You have to use "ToolStripDropDownMenu" this way -
((ToolStripDropDownMenu)noMargins.DropDown).ShowImageMargin = false;
For example, if you want to remove all image margins from your menubar called "menuStrip1", add this code to your form initialization routine -
foreach (ToolStripMenuItem menuItem in menuStrip1.Items)
((ToolStripDropDownMenu)menuItem.DropDown).ShowImageMargin = false;