Q: rescue email

Various available options are listed here.

https://support.apple.com/en-us/HT201487

https://support.apple.com/en-us/HT204152

Best.

If you have formed web mail as gmail there is a method :

1. open web mail via safari & enter your gmail id .

2. Uncheck the box stay signed in , enter your password & click on next .

3.take your cursor on top extreme right side & click on google apps .

4.Click on my account .

5. select security check up & click on get started click on done , follow the steps in-between an option will be seen rescue mail . you want to remove .

Pardon me , i just guessed are you stating about gmail rescue password as in the question it was not clear .