Normally we’d invite you to search the forum for the extensive discussions around this matter, but before @KrishnaIyerEaswaran2 enters the same state of despair as I am in, here’s the short answer:
Registered TTIGs have to be deleted and claimed as per the instructions.
The EUI is NOT the ID
The ID is some made up identifier that does not already exist for anyone of any type on TTS CE - so it is likely that “my-gateway” has been used as has “nicks-awesome-gateway” etc etc
So you will need to come up with a new ID as you can’t reuse an ID for a deleted Gateway or Application - this is non-negotiable and is required for data integrity and security on TTS.
So you press the claim button that has been on the console for about 10 days now, enter the details as appropriate and click the Claim button.