reset my 6 but forgot my old account

Activation Lock Problem

If you purchased the device second-hand, then it is useless without the Apple ID and password to which it is locked. If you don't have it, can't remember it or cannot get it, then the device is useless to you. Try to get your money refunded, if you can, or take it to an Apple store for an exchange provided they will help you. If you are the original owner then take the device, a copy of your purchase receipt and identity proof to an Apple retailer where they may be able to assist you.

Find My iPhone Activation Lock

If you can't activate your iPhone - Apple Support

For Problems With Your Apple ID

1. Forgot iCloud Password
2. Forgot Apple ID
3. iForgot Password - Apple ID
4. iForgot UserName - Apple ID
5. Apple ID - Apple Support
6. Manage your Apple ID primary, rescue, alternate, and notification email addresses
7. About your Apple ID email addresses
8. Get help with Apple ID
9. Contact Apple for help with Apple ID account security - Apple Support
10. What to do after you change your Apple ID email address or password - Apple Support