Ask an Property Solicitor. Get an Answer ASAP.
I am a solicitor.
You may send her a note asking her to remove it from your property within say 7 days failing which you will remove it from your property at her risk as to any damage.
May I help further?
Sure, please see here re: ownership of airspace.
All the best
Please see here: https://www.inbrief.co.uk/land-law/land-ownership/
You are welcome.