That should work perfectly as a focus light though- when you're shooting macro you'd 'normally' be shooting with apertures of f.8 or lower which will block out almost all ambient light, even from a fairly powerful torch. Don't worry too much about it if it doesn't turn off, theres ways around it.
To test it, try to take a picture with your "standard macro settings" mine are ISO 100, f.8, 1/250, but only leave your torch on, turn off your strobes, then you will see if the torch affects your image at all, ideally the shot should be completely black 
If the image is lit up by your torch then you have three options:
1: Stop down your exposure a little until the image is black (not recommended if you want the nice bokeh found around f5.6-f8)
2: Put extra diffusers on the torch to reduce the strength (pieces of tupperware or white plastic bags work well)
3: Buy a weaker focus light
Hope this helps- Morten