Web Editor issue: Cannot DELETE Library

Create Editor uses this way of understanding which library to use:

First of all it gives precedence to custom libraries.
Then it gives precedence to libraries that were included from the library manager with a specific version (not latest)
Then it chooses a library from all the other libraries that share the import (it's not deterministic, though)

So to avoid conflicts there are two ways: upload a custom version of the library you want to use, or select a specific version of the library you want to use.