Huawei P9 - Manual (Page 11)

Phone manager
Touch .
You can quickly scan your
phone for potential risks with
one touch. Follow the
onscreen instructions to use
one-touch optimization, or
manually clean the system
storage and manage your
applications.
Touch the options on the
screen to clean your system
trash, set the harassment
filter, activate power saving
mode, manage your
applications' notification
permissions, and more.