On the fieldTask main screen there are 3 tabs
All the blank surveys that are available to be filled in. Select a survey in order to fill it in. Once you have completed the survey an instance is created that is then submitted to the server. The blank form will still be present ready to be completed again.
Any tasks that have been assigned to the user as well as completed or in progress instances.
Once an instance has been submitted to the server you cannot modify it. These submitted instances will disappear the next time you do a refresh.
An instance that is finalized, that is has been marked as complete but not submitted, cannot be edited however you can review the data and add notes. However this ability to review the data in a finalized survey while it is on the phone can be disabled by a setting in the Mobile App Options tab on the user management page.
Incomplete instances can be opened for editing. If you do a long press on an incomplete instance or task then you can reject it. Effectively it will be deleted. You need to provide a reason for this action.