Firstly, please delete/forget the pairing history of Liberty 2 Pro + on your devices.
Then place the earbuds back into the charging case and keep the case open, tap and hold the button at the back of the case for 10 seconds until both the earbuds' LED starts blinking red 3 times. This will clear the pairing information and the reset will begin automatically.
If you have additional questions, please contact us at Service@soundcore.com for further assistance. Make sure to mention that you have tried the steps in this FAQ so our agents do not ask you to repeat these steps.