If the phone is frozen, remove the battery (if removable) or hold the Power button for 15 seconds until it turns off.
If the problem persists after a hard reset, consider visiting an authorized TECNO service center, as the issue may be hardware-related.
Is your TECNO Phantom 6 acting sluggish, freezing frequently, or asking for a password you have forgotten? If you are searching for "Comment réinitialiser TECNO Phantom 6" (How to reset TECNO Phantom 6), you are likely looking for a way to either refresh the system or completely wipe the data to solve a software issue.