Managing local package and artifacts repository

I recently found out that my ~/.julia package was taking about 20GB

I deleted the directory, and started afresh

Are there any “best usage” tips for maintaining a lean ~/.julia directory?

This was discussed recently. Try using the gc function in Pkg
As I recall that thread said that gc did not work as efficiently as expected.

help?> ? Pkg.gc
Pkg.gc()

Garbage collect packages that are no longer reachable from any project. Only packages that are tracked by version
are deleted, so no packages that might contain local changes are touched.

thanks
I am aware of gc, but it did not reduce the size of the .julia directory. I had a large number of files in the artifacts subdirectory which gc did not remove
For example, when I build a package with BinaryBuilder in a project directory and perform activate . to make sure that everything is installed in the context of this project/directory, and I later want to discard that project - deleting the directory has no effect on the artifacts that are stored in ~/.julia.
What is the proper way to signal to the package manager that a project is deleted and that its related files can be freed?