deleting old messages off in reach mini, via sync, and old tracks too

I want to delete several threads of old message from my in reach mini device.

I would expect that I could go to my website and delete them there, then do a sync.

This does not remove them from the device.  I have noticed while syncing, that it does not go thru a step called "messages". It goes thru firmware, contacts etc.

Question:  Is the only way I can remove them, is by doing it on the device ?  

SO the SYNC is not truly a SYNC, for messages ?

BTW, the same is true for track logs:  You must clear the track log on the DEVICE AND THE WEBPAGE, or they will re-appear, when you sync.

SO SYNC, IS NOT REALLY A SYNC.