Hello! I am looking to buy a house as an investment property. The attic wiring is not up to code, but we are not planning on using it for anything except for storage. Can the old wiring just be removed, or does it need to be brought up to code?

It should be removable.

Hi Molly,

You don't have to bring ANYTHING up to the current code. If it is old, but passed when it was installed, it is grandfathered.

Home inspectors often don't realize that.

If there is a problem with the wiring however, then it needs to be fixed.

If it is not safe, it needs to be removed or replaced. If it was up to the old code when installed, there is no need to do anything, at this time. But are you sure, that other wiring hidden is up to code, one area of out of code is often a signal for more.

If it was questionable in the attic, God only knows what it is like in the inaccessible areas. Either have it checked out thoroughly or pass on this house for investment.
Doesn't matter what you are using the attic for, doesn't have much bearing on the issue unless you put flammable materials there and increase the risk.
Not sure if you mean that the house will be used for storage or the attic used for storage. If you plan to re-sell it, a good inspector will bring the deficiencies to the attention of the potential buyer.
Don't assume that the wiring visible in the attic is just for attic lights and is not needed elsewhere. Most likely the wiring you see there is for circuits servicing the floor below the attic.
Get the house assessed by a qualified electrician before you purchase it.