Thank you for using Syncfusion products,
The reported requirement of disabling the dates in DateTimePickerAdv can be achieved by handling the DateCellQueryInfo event of calendar as shown in the below code snippet.
void Calendar_DateCellQueryInfo(object sender, Syncfusion.Windows.Forms.Tools.DateCellQueryInfoEventArgs e)
// This event enables user to customize MonthCalenderAdv DateCells
if (e.RowIndex == 3 && e.ColIndex > 6)
e.Style.BackColor = Color.Snow;
e.Style.Enabled = false;
// To set selectable Date cells BackColor
e.Style.BackColor = Color.FromArgb(13, 134, 64);
We have also prepared a sample and it can be downloaded from the following link:
Please let us know if you need further assistance,
Thank you for the update,
Please let us know if you need further assistance.