cant downgrade angular cli to version 8.x.x - node.js

Question

I need to downgrade my angular cli from version 9 to version 8. I have tried the following:
npm uninstall -g #angular/cli
npm cache verify
npm install -g #angular/cli#8.x.x
whenever I reinstall it and run ng --version it will still output version 9 packages:
Node: 14.3.0
OS: darwin x64
Angular: 9.1.9
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router
Ivy Workspace: Yes
Package Version
-----------------------------------------------------------
#angular-devkit/architect 0.901.7
#angular-devkit/build-angular 0.901.7
#angular-devkit/build-optimizer 0.901.7
#angular-devkit/build-webpack 0.901.7
#angular-devkit/core 7.3.9
#angular-devkit/schematics 7.3.9
#angular/cli 9.1.7
#ngtools/webpack 9.1.7
#schematics/angular 9.1.7
#schematics/update 0.901.7
rxjs 6.5.5
typescript 3.8.3
webpack 4.42.0
I really need to roll back to version 8 to fix a breaking change, but am unable to get anything to change from version 9. Running ng serve with version 9 won't compile the app. Is there something I'm missing?
EDIT: I figured out that I had somehow installed a different version of the cli specific to the project that I was working in. I uninstalled both the local cli and the glocal cli and reran npm install -g #angular/cli#8.x.x. The ng --version output is correct now but when I try to run ng serve I get the following error: Cannot determine versions of "#angular/cli".
This likely means your local installation is broken. Please reinstall your packages.

Answer 1

this worked for me:
ng --version
npm uninstall -g #angular/cli
npm cache clean --force
npm install -g #angular/cli#8
ng --version