使用单个键从关联数组中删除键

I have the following array,

$myarray[0]['first_name']
$myarray[0]['last_name']

I want to turn it into:

$myarray['first_name']
$myarray['last_name']

with a simple oneliner?

this?

$myarray = $myarray[0];

Or this?

$myarray = current($myarray);

user187291's solution still looks clearer though.