"To" addressee incorrect

[Cawshus]

How do I remove incorrect email addresses from the droplist that appear
when completing the details in the 'To' section of a new email?

 

[Mary]

Use the arrow key to highlisht the incorrect one, press Delete.

 

[Cawshus]

Use the arrow key to highlisht the incorrect one, press Delete.

Too simple for me to think of! Thank you.