can anyone explain why 20 ripple coins have to stay in my wallet? nano s

Having persuaded a friend to invest in ripple amongst other crytos, we have come across a surprising 20 amount, that stays in the nano s ledger.
When these were at 15 pence, that was hardly an issue, though with them going past the £1 like today, it means £20 locked in, that he/we can never access, now imagine if they reach £100 each or more, then the locked 20 will be insane, to never be able to touch.