My boat is a 2002/3 Bavaria 36, and the bow roller and plate it is welded to was definitely not glued on. The three bolts used are more than capable of holding it in place. If yours is glued on, then that has to be something done by a previous owner, and you may well wonder why. If you have the name and address of that previous owner it may be worth while trying to contact them to enquire what kind of glue was used and hopefully why, because if glue was used, then grinding off a few millimetres of steel from around the perimeter will not release any glue that may be between the plate and your glass fibre deck. Sikaflex, if that is what has been used, is a sealant rather than a glue, and will release the plate if some persuasion is used by way of a lever, but you would need to protect your deck from damage under the fulcrum used by the lever. Be aware also that the perimeter of that steel plate, if I remember correctly, does curve slightly under the edge of the deck, and hence the need to be able to release the forestay attachment to allow the plate to be moved forward to clear the edge of the deck.
Have you checked the under side of the deck to ensure there are no other securings that may have been fitted by a previous owner?
Using an angle grinder to remove parts of the steel has to be a very last resort, as much as anything it will create a lot of heat, and glass fibre does not need much encouragement to catch fire and burn very vigourously !!
