You can always activate an ability that will cause a creature to adapt. As that ability resolves, if the creature has a +1/+1 counter on it for any reason, you simply won’t put any +1/+1 counters on it.
2019-01-25
If a creature somehow loses all of its +1/+1 counters, it can adapt again and get more +1/+1 counters.
: Adapt 2. (If this creature has no +1/+1 counters on it, put two +1/+1 counters on it.)
Each creature you control with a +1/+1 counter on it has flying.
: Adapt 2. (If this creature has no +1/+1 counters on it, put two +1/+1 counters on it.)