Deleting email addresses that are not in contacts

[bigbert1]

Hi, .... Hope for some help
I use an N10 with Gmail app. When filling in the To: field on Gmail, an unwanted email address pops up as available to select. I have deleted it from Contacts; it does not show under contacts/"other" on desktop Web app and does not show up when contacts are searched. When using the Web based Gmail app, the offending address does NOT show as available to select.
I have tried many suggestions, but cannot find a way to delete it. It seems like it is stored somewhere in the tablet (can't find problem in Chrome auto-complete setting, nor in SwiftKey "learned words"). Suggestions welcome.

 

[Rukbat]

Try clearing the cache in the email app. If that doesn't work, try clearing the data (with airplane mode enabled).

 

[bigbert1]

Thx Rukbat. Tried both (in airplane), but address is still presenting itself. This originally happened when a friend was hacked and changed his email. I went into contacts and edited/entered his new one. Web based Gmail works fine. Tablet Gmail app presents both old and new addresses. No sign of old address in contacts, chrome auto fill or SwiftKey. Strange.