charge mixer eccentric bottom bracket

EBB are a piece of piss to maintain;

FTFY

is it possible to remove it and grease it

Yes.

1.Remove cranks

1. Loosen bolts that hold the EBB in place (under the bb shell).
   
2. Slide EBB insert out to the side.
   
3. Clean/grease/refit.
   
   

The bolts that hold the insert in place can chew up the insert. In this case it may be difficult to remove but a dunt from a mallet should get it out. SJS sell replacement Thorn inserts and Ithink they are mostly all the same size, ones that are held by bolts underneath anyway.