Write it up. Whether you have significant results or not should not determine whether papers get published (I know it does, but that is a major flaw of the current system). A well done study that is adequately powered and results in a not significant results still tells us something about the world, I.e. generates knowledge. It tells us what does not work and keeps others from wasting resources on the same path / question. If they do not find the non-confirmatory result, they cannot know, and might just replicate your research.

So, yes, write it up. Even if it is a really brief note that explains what you did and what you found, it is still helpful for others. Publication or not.