How do I remove an old Franke monobloc kitchen tap?

I want to change our old, leaky Franke kitchen monobloc tape for a new one. Since I didn't fit the old one, I don't know how it is fastened in, and of course there is no view because the sink unit is in the way. I can see the plumbing - no problem - and by feel there is a long shank extending downwards from the tap base, next to the pipes, with a screwhead type cut at the end. Is this the key to getting it out?