As to pruning, fronds that are still partially green should be left on the palm. They continue to photosynthesize and provide ...
But this is the worst thing you can do for your bougainvillea.
However, if you can determine what is dead and what is alive, prune now ... like the windmill palm (Trachycarpus fortunei), jelly palm (Butia capitata), cabbage palm (Sabal palmetto) and native ...
If you must prune them, do so by hand ... I have some doves nesting in the sabal palm outside my window and it’s fun to have them always peeking in at me. I’m assuming that bats are living ...