Package 'rviz_common' not found

[sisaha9]

I keep getting the below error when running rviz2

terminate called after throwing an instance of 'ament_index_cpp::PackageNotFoundError'
  what():  package 'rviz_common' not found, searching: [/home/user/ws/install/pkg1, /home/user/ws/install/pkg2, /home/user/ws/install/]

It was working before but after removing a workspace it kept giving me a warning

WARNING:colcon.colcon_core.prefix_path.colcon:The path '/home/user/old_ws/install' in the environment variable COLCON_PREFIX_PATH doesn't exist
WARNING:colcon.colcon_core.prefix_path.colcon:The path '/home/user/old_ws/install' in the environment variable AMENT_PREFIX_PATH doesn't exist
WARNING:colcon.colcon_core.prefix_path.colcon:The path '/home/user/old_ws/install' in the environment variable CMAKE_PREFIX_PATH doesn't exist

I edited these paths manually to try removing the errors and I think it screwed things up. Is there a way to completely reset everything/clean everything and start from scratch?

[sisaha9]

Resolved after restarting machine. Would still like to know if there is a command to clean a workspace

[dirk-thomas]

Would still like to know if there is a command to clean a workspace

No, there is not atm: colcon/colcon-core#37.