Help punching a hole

Rhino Rhino for Windows
#1

I created a surface (many actually) now I want to put a circular hole (several of different sizes to be accurate) in the surface. Neither make a hole or boolean operations seem to cut a surface. I tried converting the surface to a mesh and using a mesh sphere as the boolean cutter- no luck. I tried converting the surface to a nurbs object with SrfPrt- nothing.

The surfaces were created from 2 curves using the EdgeSrf command.

How can I punch circular holes in them?

#2

Trim command should do.
Or wirecut command.
No need to change to meshes.

#4

trim worked, thank you.