Great Question @putta.anusha , Welcome to Apigee Community,
When you use the Drupal Developer portal, if you delete a user in the administrative panels for Drupal, the following things happen,
- Apigee module deletes the Developer Account from Apigee.
- This also causes All developer apps to be deleted. Any keys/credentials associated to those applications will become invalid.
- Apps may function for few (~3) minutes due to cached keys or tokens. After the cache expires, all the keys / credentials will become invalid. VerifyAPIKey on those keys will fail. OAuthV2/VerifyAccessToken will fail.
- As a result of those failures, Apps that depend on the de-activated credentials will stop functioning; you will see "Unauthorized" errors.
I hope this helps.