How to delete UVmap island?

I want to delete a selected UVmap island.

How to delete a all island or selected island from UVmap or UVmap.001?

That is to say, I want to Dis-Unwrap.

Please answer to me.
Thank you.

You cannot have faces that have no UVs.
You can reset their UVs to the default (every face being the UV space) by selecting the faces and in the 3d view use U / Reset

Just erase or separate those faces from your object.