General:
* Interchangeable: This implies that two or more things can be used in place of each other without any significant difference.
* Substitutable: Similar to interchangeable, this emphasizes the ability to replace one thing with another.
* Reversible: This implies that a change can be undone, going back to the original state.
More specific:
* Switchable: This directly indicates the ability to switch between two or more states or options.
* Mutable: This emphasizes the ability to change or be changed, potentially implying a more permanent shift.
* Toggleable: This specifically refers to the ability to turn something on and off, like a switch.
The best word will depend on the specific context and what you want to emphasize.