M-x helm-locate
lists files in hidden folders, that i will never open. How to instruct helm not to look into certain directories for file search & open.
helm-locate uses linux command locate which uses updatedb to index the file location. To ignore some directories, configure /etc/updatedb.conf as
PRUNEPATHS="EXISTINGPATH NEWPATH"
And run updatedb in shell prompt with sudo permissions to get this change reflected.