So if you're an Active Directory sysadmin and want to disable the #Perplexity AI search engine from your users' #Firefox 144 installations:

Install the Firefox .admx policy definition file on your domain controller.

Add and link a group policy object.

Edit the policy, navigate to User Configuration\Policies\Administrative Templates\Mozilla\Firefox\Search\Remove Search Engines

Enable the item.

Add an entry that reads (case sensitive): Perplexity

Next time your users start Firefox, Perplexity is gone.