"De-colonize your Narrative" is one of those phrases that tends to trigger people.
But if we break it down, it's really quite simple and non-threatening. Let's look at it through the analogy of children's books.
A "narrative" is simply "a story", or a "spoken or written account of connected events". We all understand that the "narrator" is the one telling the story. In children's books, there exists the most diverse range of narrators and narratives. For the simple fact that children are encouraged to indulge in their imagination and love for all beings. So, stories are told of course about children, all different types of children, ages, races, genders, religions, abilities, but also, good children, naughty children, clever children, artsy children, day dreaming children etc. etc. But beyond a human narrative, children's books easily immerse us in narratives of animals, nature and other non-human, non-traditional points of view.
"De-colonize" simply is asking you to take the story, the narrative, that is your foundation for reality and open yourself up to the fact that your story, your narrative isn't the ONLY ONE that exists. That's all.
So just like children love to listen to all sorts of stories, a wide variety of narratives.
We as adults, would create a world with more justice and compassion, if we were open to listening to and embracing ALL people's stories and narratives of OUR collective history.