How to Enable/Disable MenuStrip Items and Item's Drop Down Collection Items In C#

I want to know how can I disable/enable a MenuStrip Item and How to disable/enable a menustrip item's DropDownCollection particular item.

A Picture is given of my menustrip and "Account Department" is the DropDownCollection Item Which I want to Disable/Enable according to conditions.

I have a line of code which disable Main MenuStrip Item in this case "Departments" is the Item.

That line of code is:

menuStrip1.Items[1] = false;

Currently I have no right to upload a picture so here is a link to it

Image Link