Volunteer activity form: remove requirement for volunteer to enter mailing address

We use the volunteer activity form on our website. Please remove the requirement for volunteers to enter their mailing address every time they enter volunteer activity. On the volunteer signup form it makes sense, but not everytime there is activity.

Our webmaster helped us "hide" the address so it's not seen by volunteers, but this doesn't help. In this case Bloomerang creates a blank default address, that we have to fix.