Check out how to easily wipe cache partition in MITO A91 Fantasy Fly. This operation won't affect your personal files it will only remove temporary cache files. As a result you can refresh Android 6.0 Marshmallow system and optimize .
Begin this operation by switching off your device, so just hold down the Powerkey for a couple seconds.
Afterwards, hold down the Powerkey and the VolumeUp button together till you see the BootMode menu.
In this menu you have to scroll down by using Volumebuttons and chooseRecovery by pushing the Power key.
In the Recoverymode, navigate yourself down and choose "wipecache partition".