How do I remove mods from a world when creating it?

Playing on Android and I can’t figure out how to remove mods from a world while in creation, or how to remove them from the default.

You swipe to the left or right then swipe down/up until you get to the mod you dont want, then just tap. It’ll be gone. To save a new default, press s.

I swear I tried that, but it worked.
Guess I goofed up somehow.