A property owner is free to trim or prune any plants that extend onto her property.
If you want a higher hedge, plant a new hedge that is entirely on your property.
If this answer was helpful, please mark it as helpful or as a best answer. This answer is for general education purposes only. It neither creates an attorney-client relationship nor provides legal guidance or advice. The answer is based on the limited information provided and the answer might be different had additional information been provided. You should consult an attorney.
You have the right to trim the branches of the hedge that extend to your side of the property in any manner you want. Your neighbor has the right to trim the hedge branches that extend onto her property. Neither of you has the right to restrict the right of the other to trim the hedge. The aesthetics of the trimming job have no bearing on your legal rights. If you are unsure of your rights or obligations, you should consult an experienced real estate lawyer in your area.
Disclaimer: This answer is provided for informational purposes only, does not constitute legal advice, and does not create an attorney-client relationship. Actual legal advice can only be provided after completing a comprehensive consultation in which all of the relevant facts are discussed and reviewed.