If the tasker has started working on the task (making it partially completed), they may be entitled to some payment in recognition of their time and effort.
In cases like these, instead of cancelling the task, we recommend discussing a partial payment amount with the other member via Private Messaging. If you've agreed to a decreased price, contact us here so we can make the adjustment for you.
If you can't agree on a different price, Airtasker can help with our dispute resolution process. For more information on this process, see our range of helpful articles here.