For anybody in 2025:

conda deactivate

This will deactivate (base) environment.

As of Anaconda Distribution 2025.06, an uninstaller.sh script is available to help you remove Anaconda Distribution from your system.

https://www.anaconda.com/docs/getting-started/anaconda/uninstall#macos-or-linux

~/anaconda3/uninstall.sh

This will remove all packages and miniconda itself.