Apple TV passcode

Seems you have added a restrictions code:

Use Restrictions on your Apple TV - Apple Support

If you forgot it you will have to reset your Apple TV

Settings>Reset>Reset All Settings

You will then reset all settings to standard and you will have to set up the apple TV again as new.

Reset Apple TV - Apple Support

Good luck!

A Restrictions password is needed to unlock whatever was restricted. The only way to resolve a forgotten PIN, is to reset to factory settings.

Use Restrictions on your Apple TV - Apple Support