WhatsApp does not offer a built-in option to fully hide a group
Archive the group chat
Mute the group notifications
Turn off chat previews in notifications
Lock WhatsApp with a screen lock or app lock
Use fingerprint or face lock for WhatsApp if available
Leave the group if you do not want it visible anymore
Delete the group chat from your chat list
Clear media from the group if needed
Restrict WhatsApp notification access on your device
Use a separate phone number or account for private groups