Clearing Saved Logins I have a Nexus 5x that is proving quite troublesome (overheating/rebooting) and needs to be sent back to supplier/manufacturer. Before I send it I would like to removed saved logins and passwords. These are for the Gmail account linked to the phone and a number of professional websites - there are confidentiality issues. Can this be done or would I be best just changing the passwords from another system?
You can do a simple factory data reset. That's a good enough bet.

Additionally, even if you don't reset it manually, it'll likely be reset by the repair shop.