An issued developer token is a unique combination of letters, numbers, and characters that is required for communicating with the AdWords API server. It authorizes your AdWords API activity and thus you should treat it like a password.
You should reset your developer token if you believe that it's been compromised, or if a team member who has knowledge of the token has left.
What happens on reset?
Note that a reset will immediately invalidate your previous token, so any API requests using the old token will fail. However, a reset will not trigger re-review with the compliance team for an approved token. You can start using the new developer token immediately.
How do I reset my developer token?
Go to your Manager account in AdWords.
Click the gear icon on the top-right of the screen:
Select Account settings:
On the left menu, select AdWords API Center:
In the Developer details section, you will see your developer token:
Click Regenerate token.
Tip: While your're in this section, confirm that your API contact email is a valid email address that's actively monitored by your team. It's recommended that this address be for a team instead of an individual.