I realized the silicone had not yet dryed up in it's tube. I had been pretty certain that the nozzle would be totally clogged by now, but it wasn't. Which was good because A found yet another place where to use it.
I removed it with the carped knife like I did in the toilet. This area was so small that removing the silicone took only like two minutes.
Then I taped the edge and squeezed the silicone. Then I evened it with my finger. And Tadaa! it's done. That took like fifteen minutes. Now I think there is not enough silicone in the tube to fill even this small gap.
PS. Incase you are interested, I have painted a lot in the office, there are some layers of paint still needed both on the wall and on the shelf. But it's not a huge job anymore.