Can I delete the address?
The wallet has some 100 addresses pre-generated, so when you create a new address it simply becomes visible.
You cannot delete the address and there is a simple reason for this: the address is already known to someone and some coins might arrive at it. If the address is deleted, coins might disappear.
However you can delete the address from the recipients’ address list (in menu File - Sending Addresses, i.e. address you ever sent the coins to). It is possible because those addresses do not belong to your wallet.