It is impossible to totally remove a park reference from either WWFF or POTA reference boxes.
Backspacing all the contents results in the first letter re-appearing or being re-inserted when the box or QSO is re-saved.
Editing a frequency also requires significant patience to avoid the first numeral in the box bouncing back in front of the newly edited/inserted frequency.
Alan
I had this experience on the “Notes” field. Had added a word for testing purposes to a QSO and could not delete the content completely afterwards. Had written then 1 space to store something invisible, but I don’t bring away this “Notes” entry.
Vy 73, Markus