How do you get rid of the lvl 30 ghost in Pokemon tower red versoin?

The Level 30 ghost in Pokemon tower is a dead Marowak that was killed by Team Rocket. To get rid of it you have to go to Celadon City and open up the basement in the game corner. This can be done by pressing 'A' on the poster on the wall. Now go into the basement, defeat all the Rocket Grunts and their boss, Giovanni, and he'll give you the silph scope. Now go to Pokemon tower with the silf scope and you can defeat the ghost.