With the recent release of FIO 2.3 on the FIO Protocol Mainnet, you can now transfer FIO Addresses, as long as they haven't already been used with FIO Requests or FIO Sends with metadata.
The FIO address transfer functionality will be added to FIO enabled wallets on their own schedule, but you can also use Anchor by Greymass (the mobile experience is the best) and http://fio.bloks.io/ right now.
Just click on More and then Tables + Actions:
Next type in fio.address for the Contract Name, hit enter or click Get Contract and then select xferaddress:
This next part may look a little scary, but don't freak out! You got this!
Make sure you're logged in to bloks using Anchor for the FIO Account which owns the FIO Address (username@domain) you want to transfer. If you haven't yet imported your private key into Anchor, do that first so you can login. If you only have a seed phrase, you can get your private key as described here or check with your wallet provider for how to export your FIO Private key.
Enter the FIO Address you own and want to transfer. Again, it must be one that hasn't been used for FIO Requests yet (a future update will allow for these to be transferrable also).
Enter the FIO public key for the account you want to transfer the address to. If you're not sure what the public key is (it starts with "FIO"), you can search for the account by FIO Address using http://fio.bloks.io/ and copy it from there.
Example if I wanted the FIO Public Key for luke@stokes:
For the max_fee field just put in a large number like I did in this example or you can actually go to https://www.alohaeos.com/tools/fiofees and get the current fee set by the block producers and multiply it times 1000000000.
To get the actor, copy the value for the account name from bloks.io for the account that you are logged in with which owns the FIO Address you want to transfer.
Click Submit Transaction and sign it with Anchor and you're all done!