In order to hard reset a Acer Liquid E3, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Acer Liquid E3 device will be brought back to the default configuration of a brand new device.
1. Power off the phone to begin with.

2. Now you have to press and hold together Volume Down + Power button until the phone vibrates once.

3. Quickly release Volume down and press Volume up. You will see a new menu on screen.

4. Next, use Volume buttons to select option "Recovery".

5. Choose "Wipe data/factory reset" option from the Recovery mode menu, using Volume buttons to scroll to options, and Menu button to confirm.

6. Press the "yes - delete all data" option.
7. Finish by selecting option "reboot system now".