Check out how to easily wipe cache partition in ZYNC Z99 Plus 2G. This operation won't affect your personal files it will only remove temporary cache files. As a result you can refresh Android 4.0 Ice Cream Sandwich system and optimize Cortex .
Start by switching off your device, you can make it by holding down the Power key.
In this step, you should hold Power and Volume Up buttons simultaneously.
Now you should be in Recovey Mode.
Scroll down to "wipe cache partition" by using Volume Down key and choose it by pushing the Power key.