Long press on the account > Options and folders > Account options > Deleting messages > Hide in the app, keep on the server.
Note that this will literally -hide- the messages in AM. Technically they're still in the inbox on the device, but if you want to see them you'll have to open the account > tap on the three dots in the upper right corner > tap Restore hidden. They will stay on the server which will allow you to download them to your laptop.