Inherited USA Ira for Spanish Resident

Big question is: are you a US citizen and if so, do you have a US IRA already established? The easiest way to do things would be to simply roll over the inherited IRA into your already established IRA or 401K plan. If you don't already have an IRA (or other similar deferred taxation plan) set up to receive this sort of thing, you may find that you need to (or may simply prefer to) pay up any taxes due as though the entire amount had been distributed to you and that way you can go your merry way and just invest the money that is left however you please and with whatever brokerage or investment company you choose. Otherwise, you're probably going to be limited to leaving the funds in the US (i.e. to set up a regulation IRA ) and you won't be able to touch them until you are eligible to withdraw funds as a "pension."

This is the info directly from the IRA website about IRAs - be sure to check the publications cited on the page because they have sections on "How to handle an inherited IRA" which is what you need to refer to.
(If by chance this is a Roth IRA, your citizenship or lack thereof will be the main determining factor.)