You can uninstall Android support (and of course you can choose to never install it in the first place):
# remove the package
devel-su pkcon remove aliendalvik
# disable the repo if you want
ssu dr aliendalvik
You can also do the first part from the Store application from “My Applications”
You can not uninstall “all Android stuff” because parts of SFOS basically function as a wrapper around a base Android install so there is always a core Android environment running…