Open the aircraft profile that you want to unlink records from. Then, navigate to the section of form you'd like to unlink. Every container has a list of all the reports attached to this aircraft.
To unlink a report click on the broken chain link icon in blue under the "Unlink" header.
That button will unlink the report from the aircraft.
If you make a mistake and want to link a recently unlinked report back to an aircraft here is a helpful link- https://help.airworthy.com/linking-a-work-order-to-an-aircraft-profile