At this point, while participants can enter pledges into their HQ (more information on this process here) , they are not able to confirm these pledges themselves. These pledges enter the organization's system as Pending Donations, and are confirmed by the organization (more information on this process here).

Allowing participants to confirm pledges would increase the total amount raised for your event.  While the participant may have the money in hand, since it has not been received by your organization we do not allow participants to confirm pledges to make tracking received money easier for the organization.