Currently Being ModeratedNov 3, 2012 5:16 PM (in response to Derekeys)
Open Messages on you mac. Click on the last message you want to sync and press delete on your keyboard. Press delete as many times is need or keep holding the key if it works.
There is no fast way for iPhone/iPad as i know.
Currently Being ModeratedNov 3, 2012 5:15 PM (in response to cheonweb)
Thanks! That is a good one. Are there any ways to mass delete messages on the iPhone and iPad?
Currently Being ModeratedNov 7, 2012 12:08 AM (in response to Derekeys)
To delete all messages from one person, open message on your ipad or iphone. swipe the screen from left to right over the name of the text conversation you want to delete. A delete prompt appears on the right hand side and this deletes the entire conversation in one go.
Alternatively, if you press edit in the top left hand corner and select the conversation you want to delete, the delete prompt also appears.
Currently Being ModeratedAug 28, 2013 9:30 PM (in response to Derekeys)
I went searching for this very fix, but I didn't realize that I knew it all along. You delete the messages the same way you delete contact groups in contacts on Mac OS X.
Click on the first conversation
Hold Option + Command then press delete very quickly.
"Option" will keep that pesky pop up window from coming up, that asks you to confirm your delete. Instead it will just delete, you can press it supper fast until they are all gone.