Syncing Mobile With Other Devices

[Boto]

I have given Mr B my old android phone.  How can I change my details to his on it so that it won't sync with my other devices but will with his?  

[Buenchico]

Remove your Google account from the phone, then add his to it instead:
https://support.google.com/android/answer/7664951?hl=en-GB

[barry1010]

I would prefer to restore the phone to factory default which resets it to how it was when you bought it.

Then Mr B can start afresh.

Not as complicated as it sounds. 

[Boto]

Thanks, I'll have a look tomorrow.