Page 11 of the product catalog on their website shows some removal tools. Which you specifically need I don't know.

https://dnpgears.webnode.page/catalog/#!

https://dnpgears.webnode.page/

Still, I'd go to a shop first unless you feel you will be removing this freewheel often.

It might be possible that it is a freehub with a cassette. But their current cassettes all use lock rings. Perhaps a older model no longer made had a threaded small cog.