Perform the following steps to disable automatic snapshot for a volume, 

Disable the snapshot schedule for the volume 

Below command will disable the snapshot schedule for the volume "testvol"

filer > snap sched testvol
Volume testvol: 2 4 8@2,4,6,12,16

filer >  snap sched testvol 0 0 0
filer > snap sched testvol
Volume testvol: 0 0 0

Disable the automatic snapshot volume option  

filer >  vol options testvol  nosnap on
filer >  vol options testvol
nosnap=on, nosnapdir=off, minra=off, no_atime_update=off, nvfail=off,
snapmirrored=off, create_ucode=off, convert_ucode=off,
maxdirsize=31457, fs_size_fixed=off, guarantee=volume, svo_enable=off,
svo_checksum=off, svo_allow_rman=off, svo_reject_errors=off,
fractional_reserve=100

To hide the .snapshot directory when accessing volume content, you need to enable the nosnapdir  option

filer >  vol options testvol nosnapdir on

filer >  vol options testvol
nosnap=on, nosnapdir=on, minra=off, no_atime_update=off, nvfail=off,
snapmirrored=off, create_ucode=off, convert_ucode=off,
maxdirsize=31457, fs_size_fixed=off, guarantee=volume, svo_enable=off,
svo_checksum=off, svo_allow_rman=off, svo_reject_errors=off,
fractional_reserve=100