How do I UV unwrap something that already has seams?

[kathal-2]

Hey! I'm attempting to UV unwrap this character's head. As you can see, it already has seams cut:

The head used to be part of a UV set that was deleted. The UV shells are no longer present in the UV editor, but the seams remain.

I'm just curious, is there any way I can salvage these seams? I typically start UV unwrapping by selecting an option from the create menu, but doing this will clear the existing seams.

I've attached the .ma file to this post!