To stop users from being able to write in the SpinEdit:

procedure TForm1.Button1Click(Sender: TObject);
begin
    SpinEdit1.EditorEnabled := False;
end;

To stop users from being able to use the SpinEdit:

procedure TForm1.Button1Click(Sender: TObject);
begin
    SpinEdit1.Enabled := False;
end;

To change the steps the SpinEdit goes up and down in:

procedure TForm1.Button1Click(Sender: TObject);
begin
    SpinEdit1.Increment := 5;
end;

To have a limit on how low the number in the SpinEdit can go:

procedure TForm1.Button1Click(Sender: TObject);
begin
    SpinEdit1.MinValue := 0;
end;

To have a limit on how high the number in the SpinEdit can go:

procedure TForm1.Button1Click(Sender: TObject);
begin
    SpinEdit1.MinValue := 5;
end;

To change the value in the SpinEdit:

procedure TForm1.Button1Click(Sender: TObject);
begin
    SpinEdit1.Value := 10;
end;