This is a base environment installed by PyCall.jl using miniconda or miniforge.
If you still need PyCall.jl for something, you can try a few approaches. There is probably a conda binary located here, which you could run.
/Users/sbac/.julia/conda/3/bin/conda
You could also just move the .julia/conda to .julia/conda.bak. Then do
using Pkg
Pkg.build("PyCall")
That should download a fresh conda install into that directory. The problem is that you may need to install individual Python packages again.
An alternative is that you can configure PyCall.jl to use another Python executable via the the Python environment variable PYTHON (ENV["PYTHON"] inside Julia). See the instructions in the README below:
The newer package PythonCall.jl behaves differently and provides individual conda environments for your Julia projects. You might need to use PythonPlot.jl rather than PyPlot.jl for example though.