Sell the investment?  That'd prevent any future K-1's & income.😉

But I betcha this is a trust, and your client is clueless as to 'why' s/he gets a K-1 (and also why those mysterious distributions show up... see Susan's comment).

edit... altho, how does one get to the point of collecting SS and not being aware of a K-1/distributions???   I do have ONE client that is this clueless.