How to hide New and Delete buttons (command buttons) in form

We can change the form design property Show Delete Button, Show New Button to No.

Or using X++ code in form's init method

[Form]
public class DEV_TestForm extends FormRun
{
    public void init()
    {
        this.form().design().showNewButton(0);
        this.form().design().showDeleteButton(0);
        super();
    }
}

For COC Extension

[ExtensionOf(formStr(SMAServiceOrderTable))]
final class SMAServiceOrderTable_Form_DEV_Extension
{
    public void init()
    {
        this.form().design().showNewButton(0);
        this.form().design().showDeleteButton(0);
        next init();
    }
}