Harm is not the operative verb here...it is a question of aesthetics. They will not be 'harmed' but will look awful. Who is making you do this? HOA? City? Public utility? You would honestly likely be better off taking them out and starting again with an appropriately sized plant.

The best time to do it is in the middle of the night and hope that no one wakes up in the morning.

Geez! Yes, HOA is forcing me even though i have approval. They changed their guidelines after i got approval and now years and years later are "enforcing" these guidelines.

Good to know it won't harm them.

Thanks for feedback!

There's no grandfathering provision in the covenants or local statute establishing such? Having vested rights not being subject to subsequent whim is a major cornerstone of US law.

You are going to have fun keeping those plants from looking horrible, lots of work, dangerous ladder climbing...I'm not an HOA fan and I'd get a letter on legal letterhead.