How to get rid of (base) inside terminal app in 10.14.6?
It's a conda's environment indicator that none of the "new" environments is active, instead the default one is active. "new" here refers to those created by: conda create --name NameOfEnv python=3.6 or similar. 

For getting rid of it, add the line conda deactivate at the end of ~/.bash_profile.

Verify by conda info --envs.