A library only gets autoloaded if you omitted some declaration that is provided by this library. You simply prevent autoloading by making sure your application defines everything it needs.
The built-in editor highlights in red all calls that are not satisfied and in a little darker blue then built-in and imported stuff for predicates that will be autoloaded. Click on the call to see where it will be autoloaded from and decide whether or not you want that.
In the development version you can disable autoloading meaningfully. The stable version mostly get useless. The built-in editor there has some extra commands to deal with (library) dependencies such as ^c^d, which updates the list of dependencies in the file. If you do not like some dependency, right click it to check which predicates it resolves.
Even if you do not like the built-in editor, it can be very useful to check your code. Another option is library(check), which exports check/0 and a couple of related predicates.