To suppress warnings you first need the warning ID. To get the ID, run these two lines right after receiving the warning.
w = warning('query','last')
id = w.identifier;
Then you can turn it off, run the code, and turn it back on.
warning('off',id)
% code
warning('on',id)
Note that if your code is stopped prior to tuning it back on, obviously it won't be turned back on. Some people use try/catch to get around that.
More info
