Web
Click 'Fields' in menu on left side
Select the field from the list or click on it on the map
Click ‘…More’ in top right of pop out box
Select ‘Archive’
To unarchive a field
Click Fields in menu on left side
In the sort/filter options, tick ‘Show archived fields’
Scroll to the bottom of the fields list to see Archived fields
Click on field name of field you want to un-archive
Click ‘…More’ at top of pop out menu
Click ‘Unarchive’
Mobile
Tap on the field you want to archive on the map
Tap the three dots top right of screen
Select ‘Archive’
To unarchive a field
Tap 'Fields' in menu at bottom of the map
Tap ‘Filters’. Make sure the filters show archived fields (this is the tick next to it, make sure it’s a blue circle with a white tick’
Scroll to the bottom of your field list
Click ‘Archived’ to expand the list of archived fields
Tap the name of field you wish to unarchive
Tap three white dots at top right of screen
Select ‘Unarchive’