The Xiaomi Sound Pocket can be reset easily by pressing the volume up button and Bluetooth button for 5 seconds.
For your reference, here are more details about the reset:
This operation will clear all previously paired Bluetooth devices and restore the speaker’s volume to factory default;
Use this method if you're experiencing connection issues, switching to a new device, or want to erase previous settings for a fresh setup;
This ensures stable connectivity and optimal performance for new Bluetooth pairings.