Open you plan by clicking on the folder by your plan name to expand all of the land parcels.
Click on the three vertical dots next to a Land Parcel.
Click on Rename and the menu will open. Insert your Field Name and click on Save.
Your Field Name will now appear as your Land Parcel.
Removing or changing a field name - using defaults
If you want to remove a Field Name just click on the three vertical dots select Rename then remove the Field Name and click on Save. The default Sheet ID and Parcel ID will be used.