This method is not perfect, but can complete the work.It is not officially supported.

Delays Terralith and open the Terralith/Data/Minecraft/Dimension/folder.

Open the Overworkd.json and search (Ctrl+F) The biological group system to be removed.

Only replace the name of the biological group and ignore the number.For example, replace Terralith: Unwanted_biome with Minecraft: WANTED_BIOME.

When removing Skylands, replace them with marine types (such as Minecraft: Ocean).