Although I haven't done this myself, it could actually be easier to blank at the connection to the manifold in front. More acccessable than at the EGR valve itself.
My Multijet has a sensor which puts it into limp home mode if I blank it off completely. I have put in a partial blank, with 3 holes, at the manifold and the EGR valve.
On this note, my EGR was leaking, even though I had cleaned it with brake cleaner etc. If I hadn't the partial blanks I don't know if it could be driveable.
Anyway, i took off the EGR valve yesterday and cleaned it with Mr Muscle spray oven cleaner. Just sprayed it into all the holes and left it for half an hour, then went at it as best as I could with an old tooth brush and left it for half an hour again. This is caustic stufff so wear gloves and goggles. Rinsed it off with the garden hose it worked fantastic! I'll have to take an image of the spare one and post it here, I never realised that the valve itself was stainless steel!
My Multi now drives much better and returns better mileage - 38mpg to 46mpg.
Still not 100% perfect but I did have a spare washer after, resulting in less tension on the spring which could be the reason. When I have an hour spare in the next few weeks I'll put it on.