Messages

Hey guys, I am looking to delete all of my messages in the Message app on my MacBook Air to make more storage. However I have messages from my dad who died in 2019 and I need to keep those. Is there any way to download that whole thread or at least some of them to a document or something I can access elsewhere? My computer is operating on whatever software is right before Monterey, which is the reason I want to free up storage anyway, so I can update it. Obviously I don’t know much about computers so don’t be too mean 🤣 Thanks in advance!