Thank you very much for the answers.
I removed gnuradio by deleting my pybombs folder and deleting all files with gnuradio in the filename from my computer. Then I installed pybombs again and used it to install gnuradio. However now I have two problems that I didn't had before.
1) When I run the command: "gnuradio-companion" it doen't work if I don't first run "source ~/target/setup_env.sh".
2) When I run a flowgraph in grc with a scope sink I get the error message: "Can't load image from file '/usr/share/icons/hicolor/32x32/apps/gnuradio-grc.png': file does not exist."
Thank you so much for any help. I am new to Ubuntu so that's probably my problem..
Best regards
Carl