I can't get the latest Polybrush to work

On the Polybrush instructions page, it says that before you use the package manager to install Polybrush, you must clear any old version, but I cannot locate the folder that it tells me to delete.

Upgrading Polybrush If you have been using a version of Polybrush prior 1.0, please thoroughly follow these instructions:

Close Unity. Find the /ProCore/Polybrush/ folder. It should be located at /ProCore/Polybrush/. Delete the folder. Open Unity. Install last version of Polybrush from Package Manager (see Installing Polybrush)

I have used Windows search to look for it in all my drives, but it doesn't show up. When I install polybrush and I go to the tools menu, it still has the Z_AdditionalVertexStreams available, but the manual says that if the polybrush install is successful, this will not be there.