Good morning.
I have an arrangement to save the information of the session that I will use, it is sent to me by multidimensional arrangement but I have not been able to access the data, I can only see them through print_r.
Annex result of print_r. 
I appreciate your support, regards!
Assuming that your array is stored in the variable $ user, to access you must use two indexes. The first is the user data, and the second is the field you want to access. For example, to access the name:
$ user ['username'] ['name']
Keep in mind that to do this you must know the keys (indices) of the second level. If you need a list of these indexes, you can obtain it with:
array_keys ($ user ['username'])
The latter would return an array such that:
array(
'__ci_last_regenerate',
'logged_in',
'username',
'usuariovalido',
...
)