At the moment there is no option for turning off power ups.

It would be an easy game option to add, however you might run into problems where a hole requires a power up for a hole in one, or even requires one for getting through the hole normally. There are several holes in the official courses that require a power up for a hole in one.

I've seen others wanting an option to disable power-ups, so I suppose it is time for me to raise the priority of looking into it.

- Kevin

You can disable power ups in the Lobby now. However, there is a warning that if you disable power ups some of the courses won't play properly.

Of course, that won't be a problem on courses you build yourself.