No problem, you need the following tools: a small hammer, a dull wood chisel, eye protection, and mastic and a replaced bullnose.
Now, with your eye protection on, and all others out of the room, you want to hit the bad bull nose in the middle with the hammer as to break it up. YOu do not want to break or crack any joining tile pieces. The blow of the hammer should be hard enough to break that one.
Then with the chisel and hammer break out all the pieces and work from the center to the ends of that piece. Get all the debris out, if you do not the new piece will be slightly proud.
Now with that area clean, get some mastic or tile glue or even some all purpose liquid nails and butter that new tile up and then place it into place, might tape it to the counter with blue painters tape. Then after one day, remove tape and then do the grout work. Then wait for 3 days before getting that area slightly wet. Seal it then if you wish.