How to set Datetimepicker to Month and Year only format?

You can use DateTimerPicker.Format property as following:

DateTimerPicker.Format = DateTimePickerFormat.Custom;
DateTimerPicker.CustomFormat = "MMMM yyyy";
DateTimerPicker.ShowUpDown = true;

Note: DateTimerPicker.ShowUpDown = true; is for making the calendar not visible

This will give you some more options to display date with diff formats.

DateTimerPicker.Format = DateTimePickerFormat.Custom;
DateTimerPicker.CustomFormat = "MM/yyyy"; // this line gives you only the month and year.
DateTimerPicker.ShowUpDown = true;

Below are the different formats to display date alone on the date time picker control of the Windows applciation C#

DateTimerPicker.CustomFormat = "MMMM yyyy";

The above code will display the full month name and year like "August 2018"

DateTimerPicker.CustomFormat = "MMMM yyyy";

The above code will display the full month name, date and year like "08 August 2018"

DateTimerPicker.CustomFormat = "dd MM yyyy";

This line will give the date in the specified format with out forward slash "08 08 2018"

DateTimerPicker.CustomFormat = "dd/MM/yyyy";

This line will give more specific format to the date "08/08/2018"

DateTimerPicker.CustomFormat = "dd/MMM/yyyy";

This line give date in the format of "08/Aug/2018"

Use DateTimerPicker.Format property. Check MSDN

public void SetMyCustomFormat()
{
   // Set the Format type and the CustomFormat string.
   dateTimePicker1.Format = DateTimePickerFormat.Custom;
   dateTimePicker1.CustomFormat = "MM/yyyy";
}