How to disable text box in C#

Question

Hello friends,
DO you have any idea how can i disable text box without using properties... my client's requirment that he don't want to see some other text boxes like (middle name , Date of Admission etc.) i want to give it to use by selection now i have made the selection option but i m not getting how to disable at form load...
Please reply me ASAP..

Thanks in Advance