CB Admin can remove an environment at any time without damaging or disrupting the existing servers, which are located in the environment. This could be done by associating the servers with an unassigned environment.
CB error while attempting to remove an environment with active servers looks like this:
Error: Specific error - Environment "US East (Northern Virginia) [us-east-1] ENV-A-1" cannot be deleted, because it has 19 active servers. They need to be decommissioned or moved to a different environment first.
Step 1: Click on CB Admin -> Environment
Step 2: Select the Environment, which you want to remove, and that has active servers.
Step 3: Click on server Tab
Step 4: Select all servers
Step 5: Click on pencil (Change Owner, Group and Environment)
Step 6: In Environment selection select unassigned
Step 7: Press confirm and then can delete your Environment safely.