While the apex developer documentation provides sample code on submitting an sObject to an approval provess with apex there is no documentation on how to recall an item from the approval process.
Is this possible? If so, how is it done?
This is possible by setting the action on a ProcessWorkItemRequest to "Removed". Depending on the configuration of your approval process this option may only be available to system administrators. If the approval process is set to "Allow submitters to recall approval requests" then the submitter of the record can also recall it.