Well, the question was how to remove those messages only and not decrease logging level.
We have to provide data from severity low (users joining and leaving, rx bytes & tx bytes are computed into graphs from logs montly), we need users' sessions time.
(We would also like to have users kind of devices to perform a statistics, but as it seems to be inpossible on Ruckus we had it done on debug on external DHCP server).
So the question is still valid - is it possible to remove only those logs? Now, THEY are expensive as they are not paying back.