Depends on what's broken. The plastic handle pulls on a metal link that pulls on a small lever on the pedal assembly. Two plastic clips hold that link attached, one on each end. If the handle or its clip is broken, just grab the link and tug on it. If the clip on the assembly is broken you can reach up and pull on the lever. You're going to get smacked by the pedal when you do that. Instead, hold the pedal down with one hand, pull the lever with your other hand, then slowly release the pedal. The more pressure you put on the pedal, the easier the lever will move and release.

Can you show a picture of what the link looks like?