To clear the space used for storing temporary files a.k.a Cache, you can use a recovery loaded onto your android device.
This recovery is similar to the BIOS on a laptop or a computer.
In this instructable, I will be using Carliv Touch Recovery v2.7.
You can find unique instructions for installing CTR on your device.
I will not take any responsibility of bricking/wasting your phone, so make sure you know the basics and make a complete backup of your phone.
Step 1: Installing the Recovery
Search google and you can easily install the recovery.
Step 2: Booting Into Recovery
Once your phone is completely shut off.
Press the power/lock button of your phone along with the Volume+/ VolumeUp button. for about 5 seconds.
Step 3: Once Into Recovery
We will be clearing the cache and the dalvik cache.
once done, reboot your phone.
Step 4: Enjoy a Faster Phone.
And there you go! you have actually cleared trash from your phone, and repeat the process every month if possible.