Bluetooth trackpad not 'clicking' on my iMac when in recovery mode.

I am trying to erase the disk on my iMac. Once in recovery mode my bluetooth trackpad will move the cursor around the screen, but I cannot select any of the options. I have read on other forums that you have to use a physical click rather than a touch click. However, with the bluetooth pad there is no physical click.I have tried using the keyboard but this does not work.