If you need to get only a option from a list use radioButtons if you need multi-options form your list use checkBoxes. CheckBoxes can be all unchecked. RadioButtons can have only one active one and that active one can't be unchecked. Try to drag your radioButtons to an GroupBox and then you will create groups of radioButtons that will work individual from the rest. Then you can disable your radioButtons like this when you click your ClearButton:
groupBox1.Enabled = false;
or
groupBox1.Hide();
You can also try if it helps you:
SessAM.Enabled = false;
Good Luck!